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. 2021 Sep 22;16(9):e0257594. doi: 10.1371/journal.pone.0257594

Sarcopenia increases the risk of post-operative recurrence in patients with non-small cell lung cancer

Yo Kawaguchi 1,*, Jun Hanaoka 1,#, Yasuhiko Ohshio 1,#, Keigo Okamoto 1,#, Ryosuke Kaku 1,#, Kazuki Hayashi 1,#, Takuya Shiratori 1,#, Akira Akazawa 1,#
Editor: Amir Radfar2
PMCID: PMC8457491  PMID: 34551011

Abstract

Background

Sarcopenia is among the most prevalent and serious cancer-related symptom, and is strongly correlated with a poor prognosis. Moreover, it reportedly predicts poor prognosis after surgery in patients with lung cancer. However, it is unclear whether sarcopenia directly affects post-operative recurrence. The purpose of this study was to evaluate whether sarcopenia can be a risk indicator for post-operative recurrence, and whether it suppresses anti-tumor immunity, in a cohort of patients with resected non-small cell lung cancer.

Methods

This study retrospectively reviewed the data of 256 consecutive patients who underwent curative lobectomy and lymph node dissection for non-small cell lung cancer at our institution. The psoas muscle mass index was calculated as the total psoas muscle area at the third lumbar vertebral level/height2 (cm2/m2). Sarcopenia was defined by a psoas muscle mass index of under 5.03 cm2/m2 and 3.17 cm2/m2 in male and female patients, respectively. Post-operative prognosis and cumulative incidence of recurrence rates were calculated.

Results

The 5-year overall survival and disease-free survival rates post-surgery were 59.5% and 38.6%, respectively, in patients with sarcopenia versus 81.1% and 72.1%, respectively, in patients without sarcopenia (p < 0.001). The 5-year cumulative incidence of recurrence rate in patients with sarcopenia was significantly higher than those without sarcopenia (49.9% versus 22.4%, respectively) in every pathological stage. Pathological stages II and III (hazard ratio, 3.36; p = 0.004), histological type (hazard ratio, 2.31; p = 0.025), and sarcopenia (hazard ratio, 2.52; p = 0.001) were independent risk factors for post-operative recurrence according to multivariate analysis.

Conclusion

Sarcopenia is a risk indicator for post-operative recurrence in patients with non-small cell lung cancer.

Introduction

Non-small cell lung cancer (NSCLC) is a major cause of cancer-related deaths globally [1]. Although tumor characteristics, such as histology and TNM stage, and treatment factors, such as surgery and chemotherapy, have traditionally been considered important to determine cancer prognosis, recently, patient factors like sarcopenia have started gaining attention [2]. Significant loss of muscle (sarcopenia/cachexia) is among the most prevalent and serious cancer-related symptoms and is strongly correlated to poor prognosis [2], especially in patients with advanced cancer. Several studies have recently reported that sarcopenia in patients with resectable cancers including gastric cancer [3], colorectal cancer [4], pancreatic cancer [5], hepatocellular carcinoma [6], endometrial cancer [7], renal cell carcinoma [8], and lung cancer [9] also contributes to poor post-operative survival. Poor prognosis in sarcopenic patients after surgery may be attributed to two reasons. First, sarcopenia itself is generally accepted to confer poor prognosis. Even if the cancer is completely cured through surgery, there is loss of skeletal muscle mass and strength, resulting in physical disability and death [10]. Second, sarcopenia may also contribute to the risk of cancer recurrence [10].

Skeletal muscle has recently been identified as a secretory organ, producing myokines; these may activate immune cells to suppress the growth of cancer cells [11]. Although some reports have demonstrated that sarcopenia decreases post-operative overall survival (OS) [9,12–19] and disease-free survival (DFS) [9,14,18] in NSCLC patients, it is currently unclear whether sarcopenia directly affects post-operative recurrence.

Therefore, the purpose of this study was to demonstrate whether sarcopenia can be a risk indicator for post-operative recurrence, and to examine whether sarcopenia suppresses anti-tumor immunity, in a cohort of patients with resected NSCLC.

Methods

Patients

This study was approved by the institutional review board of the Shiga University of Medical Science (Approval Number: R2020-048). The need for informed consent was waived by the institutional review board owing to the retrospective nature of the study. We accessed patients’ medical records between April, 2020 and June 2021. These records were all anonymized during data collection; we used the anonymized data for our analysis.

This study reviewed the data of 256 consecutive patients who underwent curative lobectomy and lymph node dissection for NSCLC at our institution between January 2011 and December 2015. We collected data on the following patient characteristics: age, sex, performance status, smoking history, adjuvant chemotherapy, maximum tumor size, short diameter of lymph nodes which was maximum in mediastinum or hilar lymph nodes, pathological stage, histological type, lymphocyte and monocyte pre-operative blood examination values, and the cross-sectional area (cm2) of the psoas muscle at the third lumbar vertebral (L3) level on computed tomography (CT) scans. Histological assessment was performed according to the histological classification of the World Health Organization. The seventh edition of the TNM classification for lung cancer was used for pathological staging. Hematological data was collected from each patient within two weeks prior to surgical treatment. We also recorded the pre-operative lymphocyte-to-monocyte ratio (LMR), which was calculated by dividing the absolute lymphocyte counts by the absolute monocyte counts. We used an LMR cut-off value of 3.2, as previously reported [20,21]. We excluded the following cases: limited resection, incomplete resection, and no CT image at the L3 level.

Definition of sarcopenia

We used the psoas muscle mass index (PMI), which had been reported by Hamaguchi et al. to be a diagnostic tool for sarcopenia [22] and was often used in many reports to predict post-operative outcomes in patients with NSCLC [9,16–18]. Preoperative CT scans were performed within three months prior to surgery. The cross-sectional areas (cm2) of the right and left psoas muscles at the L3 level were measured by manual tracing of CT data using Shade Quest View R (Fujifilm, Japan). Subsequently, the total psoas area was normalized for height. The PMI was calculated as previously described [22]: PMI = total psoas muscle area at the L3 level/height2 (cm2/m2). Since no consensus currently exists on the PMI cut-off value of sarcopenia to predict recurrence, we defined sarcopenia as a PMI of under 5.03 cm2/m2 in male patients and 3.17 cm2/m2 in female patients. We derived these cut-off values to be good indicators for recurrence. In predicting recurrence, this definition had a sensitivity of 67.2%, specificity of 57.1%, and area under the receiver operating characteristic curve value of 0.631 in males; in comparison, those for females were 68.4%, 59.4%, and, 0.590, respectively (S1 Fig). In addition, we created another group which included patients who underwent curative lobectomy and lymph node dissection for NSCLC at our institution in 2016; this was the validation cohort. In this cohort, we analyzed the association between sarcopenia and post-operative recurrence using our PMI cut off values, and assessed the plausibility.

Post-operative outcomes

Post-operative outcomes were represented by the OS, DFS, and cumulative incidence of recurrence (CIR). OS was defined as the interval between the date of surgery and the date of death. DFS was defined as the interval between the date of surgery and the date of death or cancer recurrence (confirmed using an imaging test). CIR was defined as the interval between the date of surgery and the date of cancer recurrence (confirmed using an imaging test) and was set as the primary variable. Most patients were followed up postoperatively every three or six months, until the fifth year after surgery. Screening examination included tumor markers, chest and abdominal CT, and cerebellar magnetic resonance imaging. Bone scintigraphy and positron emission tomography CT were performed on demand. The 5-year OS, DFS, and CIR were compared between patients with and without sarcopenia.

Statistical analyses

Statistical analyses were performed using SPSS Statistics for Windows, version 25 (SPSS Inc., Chicago, IL, USA). Associations between variables were analyzed using Fisher’s exact test. The t-test was also used to compare the means of parametric data between the two groups. The Kaplan-Meier method was used to determine OS, DFS, and CIR. The log-rank test was used to compare survival differences for each variable. The Cox’s proportional hazards model was used for multivariate analysis. Statistically significant differences were defined as p < 0.05.

Results

Patient characteristics

During the study period, 354 patients received surgery for NSCLC at our institution. Among them, we excluded cases with limited and incomplete resections; 256 cases of curative lobectomy and lymph node dissection were therefore included in this study. The median follow-up period was 44.9 months. The patient characteristics are shown in Table 1. The mean age of patients with sarcopenia were higher than those without, and there were no significant differences in the distribution of sarcopenia patients among various pathological stages. Adenocarcinomas were fewer and LMRs of ≦3.2 were more common in sarcopenia patients.

Table 1. Characteristics of patients with and without sarcopenia.

Variables Sarcopenia Non-Sarcopenia p value
N = 128 % N = 128 %
Age, years 0.002
 Median 70.1 - 66.9 -
 Range 51–88 47–83
Sex 0.504
 Male 89 69.5 84 65.6
 Female 39 30.5 44 34.4
Performance status 0.062
 0 96 75.0 108 84.4
 1–2 32 25.0 20 15.6
Smoking history 0.070
 (+) 100 78.7 88 68.8
 (-) 27 21.3 40 31.2
Psoas mass index (Male) <0.001
 Median 4.05 - 6.09 -
 Range 1.97–5.02 5.03–8.58
Psoas mass index (Female) <0.001
 Median 2.67 4.15
 Range 2.00–3.16 3.17–5.48
LMR 0.037
 ≤ 3.2 36 28.1 23 18.0
 > 3.2 92 71.9 105 82.0
Adjuvant chemotherapy (stage IB–III) 0.015
 (+) 44 55.0 54 75.0
 (-) 36 45.0 18 25.0
Tumor size (mm) 0.002
 Median 30.9 - 23.8 -
Lymph node size 0.002
 >1cm 29 22.7 11 8.6
 ≦1cm 99 77.3 117 91.4
Pathological stage
 I 70 54.7 76 59.4 0.449
 II 34 26.6 28 21.9 0.381
 III 24 18.8 24 18.8 1.000
Histological type
 Adenocarcinoma 78 60.9 95 74.2 0.023
 Squamous cell carcinoma 35 27.3 24 18.8 0.103
 Other 15 11.7 9 7.0 0.198
Grade of differentiation 0.125
 1 47 38.2 53 48.2
 2–4 76 61.8 57 51.8
Lymphatic permeation 0.401
 (+) 71 59.2 64 53.8
 (-) 49 40.8 55 46.2
Vascular invasion 0.019
 (+) 91 75.8 70 58.8
 (-) 29 24.2 49 41.2
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LMR, lymphocyte-to-monocyte ratio.

Survival and recurrence comparison between sarcopenia and non-sarcopenia patients

The 5-year OS and DFS after surgery were 59.5% and 38.6%, respectively, in patients with sarcopenia versus 81.1% and 72.1%, respectively, in patients without sarcopenia (p < 0.001) (Fig 1). Since the direct influence of sarcopenia on cancer recurrence could not be estimated using OS and DFS, we examined CIR. The 5-year CIR rate in patients with sarcopenia was 49.9%, which was significantly higher than the 22.4% observed in patients without sarcopenia (Fig 2). Patients with and without sarcopenia were further divided according to pathological stage. The 5-year CIR rate in patients with sarcopenia was higher in every stage than those without sarcopenia (stage I: 29.8% in sarcopenia versus 5.5% in non-sarcopenia; p < 0.001, stage II: 70.0% in sarcopenia versus 40.0% in non-sarcopenia; p = 0.030, stage III: 86.7% in sarcopenia versus 56.1% in non-sarcopenia; p < 0.087) (Fig 3).

Fig 1. OS and DFS after surgery compared between sarcopenia patients and non-sarcopenia patients.

Fig 1

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DFS, disease-free survival; OS, overall survival.

Fig 2. CIR rate after surgery between sarcopenia patients and non-sarcopenia patients.

Fig 2

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CIR, cumulative incidence of recurrence.

Fig 3. CIR rate after surgery between sarcopenia patients and non-sarcopenia patients divided according to their pathological stages.

Fig 3

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CIR, cumulative incidence of recurrence.

To assess the plausibility of our original PMI cut off values, we analyzed prognosis using the validation cohort, which included 36 sarcopenia and 46 non-sarcopenia patients. The 5-year OS and DFS after surgery were 77.9% and 50.2%, respectively, in patients with sarcopenia versus 88.0% and 66.5%, respectively, in patients without sarcopenia (S2 Fig). The 5-year CIR rate was 48.0% in patients with sarcopenia versus 29.3% in patients without sarcopenia (S3 Fig). Based on these results, we considered our PMI cut off values to be plausible, as we could demonstrate the association between sarcopenia and post-operative recurrence in the validation cohort.

Association between recurrence and clinicopathological factors

We identified the following potential risk factors for recurrence using the comparison between sarcopenia and other factors commonly recognized to predict recurrence; these included: age over 65 years, male sex, performance status 1–2, smoking history, absence of adjuvant chemotherapy, large tumor size, large lymph node size, pathological stage II and III, histological type (other than adenocarcinoma and squamous cell carcinoma), grade of differentiation, lymphatic permeation, vascular invasion, sarcopenia, and low LMR (Table 2). According to multivariate analysis, pathological stage II and III (hazard ratio, 3.36; p = 0.004), histological type (hazard ratio, 2.31; p = 0.025), and sarcopenia (hazard ratio, 2.52; p = 0.001) were independent risk factors for post-operative recurrence (Table 3).

Table 2. Association between CIR rate and clinicopathological factors.

Variables N CIR (%) p value
Patient factors
Age (years) 0.526
 < 65 76 38.3
 ≧ 65 180 34.5
Gender 0.048
 Male 173 40.4
 Female 83 35.6
Performance status 0.713
 0 204 35.0
 1–2 52 36.9
Smoking history 0.094
 (+) 188 38.2
 (-) 67 28.8
Sarcopenia < 0.001
 (+) 128 49.9
 (-) 128 22.4
LMR 0.048
 ≤ 3.2 59 44.1
 > 3.2 197 32.9
Treatment factors
Adjuvant chemotherapy (stage IB-III) 0.127
 (+) 99 53.9
 (-) 54 32.3
Tumor factors
Tumor size
 >3cm 107 43.8 0.008
 >5cm 40 55.2 < 0.001
Lymph node size
 >1cm 40 52.6 0.010
Pathological stage
 I 146 16.7 < 0.001
 II, III 110 61.6 < 0.001
 III 48 70.0 < 0.001
Histological type
 Adenocarcinoma 173 31.7 0.021
 Squamous cell carcinoma 59 36.1 0.600
 Other 24 60.4 < 0.001
Grade of differentiation 0.003
 1 100 25.6
 2–4 133 45.4
Lymphatic permeation < 0.001
 (+) 135 50.2
 (-) 104 15.6
Vascular invasion < 0.001
 (+) 161 47.3
 (-) 78 11.3
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CIR, cumulative incidence of recurrence; LMR, lymphocyte-to-monocyte ratio.

Table 3. Multivariate analysis on cancer recurrence.

Variables HR 95% CI p value
Patient factors
 Age ≧65 1.46 0.80–2.65 0.214
 Gender Male 1.00 0.45–2.22 0.992
 Performance status 1–2 0.60 0.30–1.23 0.166
 Smoking history (+) 1.11 0.47–2.60 0.809
 Sarcopenia (+) 2.52 1.48–4.28 0.001
 LMR ≦3.2 0.97 0.85–1.10 0.593
Treatment factor
 Adjuvant chemotherapy (-) 1.31 0.74–3.13 0.252
Tumor factors
 Tumor size >5cm 1.26 0.66–2.40 0.478
 Lymph node size >1cm 0.95 0.65–1.39 0.800
 Pathological stage II, III 3.36 1.47–7.70 0.004
 Pathological stage III 1.70 0.88–3.27 0.114
 Histological type Other 2.31 1.11–4.82 0.025
 Grade of differentiation 2–4 0.60 0.32–1.14 0.122
 Lymphatic permeation (+) 1.78 0.84–3.74 0.131
 Vascular invasion (+) 0.49 0.20–1.22 0.127
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LMR, lymphocyte-to-monocyte ratio; HR, hazard ratio; CI, confidence interval.

Discussion

In our cohort, sarcopenia was the risk indicator for post-operative recurrence in every stage. Reports have previously demonstrated that sarcopenia decreased OS [9,12–19] and DFS [9,14,18] after surgery in patients with NSCLC. In contrast to these previous studies, our study has two unique features. First, using CIR, we are probably the first to demonstrate that sarcopenia in patients with lung cancer directly affected post-operative recurrence. We could not determine whether sarcopenia directly affected cancer recurrence using OS or DFS, because decreases in OS or DFS are not only attributable to lung cancer death/recurrence, but also to deaths from other diseases. Indeed, sarcopenia itself is a poor prognostic factor, because the loss of muscle mass and strength results in physical disability and death [10,23]. Second, we focused on lobectomy as the surgical procedure. Previous studies showed heterogeneity in the surgical procedures included, such as partial resection, segmentectomy, and pneumonectomy; this could have affected the recurrence rate and prognosis.

We found sarcopenia to be an independent risk indicator for recurrence. Using multivariate analysis, we compared the risk of recurrence using several factors that are commonly recognized to predict recurrence. We found that advanced pathological stage, histological type (other than adenocarcinoma and squamous cell carcinoma), and sarcopenia were independent risk factors for post-operative recurrence. Interestingly, the development of sarcopenia causes a higher risk of recurrence than that of many tumor factors including histological type, grade of differentiation, lymphatic permeation, and vascular invasion (Table 3).

There may be two reasons for the association between sarcopenia and post-operative recurrence. First, tumors in sarcopenia patients have higher malignant potential than those in patients without sarcopenia. As a result, even if the pathological stages are equivalent, tumor recurrence occurs more frequently in the former [13]. In the present study, NSCLC patients with sarcopenia presented with larger tumor size, larger lymph node size, and more vascular invasion than those without sarcopenia. Second, muscles exert a potential tumor inhibitory effect via myokines; skeletal muscle has recently been identified as a secretary organ, and is reported to activate immune cells [11]. To examine the association between sarcopenia and pro-tumor/anti-tumor immunity, we used LMR, which can reflect the tumor suppressing activity of tumor-infiltrating lymphocytes and the pro-tumor activity of macrophages in the tumor microenvironment [20]. Therefore, an elevated LMR is favorable for anti-tumor immunity, while a decrease favors pro-tumor immunity. In our study, post-operative recurrences were significantly more common in patients with low LMR, and sarcopenia patients frequently exhibited a low LMR. Previous studies have reported an association between decreased lymphocytes and sarcopenia. For example, a myokine, namely, interleukin (IL)-15 was reported to have an important role in T cell proliferation [24]; exercise induces myokine IL-6, which releases and activates natural killer cells, thereby reducing tumor growth [25]. Therefore, active lymphocytes may be decreased in patients with sarcopenia, predisposing them to recurrences. One study has reported an association between increasing monocytes and sarcopenia, where the myokine irisin dampened macrophage activity in vitro [26]. Therefore, monocytes may increase in patients with sarcopenia due to the decrease in irisin, leading to recurrence. It has been reported that the peripheral monocyte count is associated with the density of the tumor-associated macrophages; this is in turn associated with tumor progression and metastasis [27].

It is unclear whether therapeutic intervention for sarcopenia can prevent post-operative recurrence. However, we believe that sarcopenia could be a treatment target to improve the outcome of NSCLC patients who have undergone surgery. One of the therapeutic approaches for sarcopenia is exercise. Chen et al. demonstrated that patients who engaged in exercise regularly during the first six months after diagnosis have significantly higher OS and DFS (hazard ratios: 0.62 and 0.39, respectively) [28]. Thus, cancer patients should not only exercise because it improves their overall health, but because as a targeted approach it may improve sarcopenia and decrease the risk of cancer recurrence.

There were several limitations to this study. First, this was a retrospective observational study; some bias associated with the study design or analysis may therefore be inevitable. Second, sarcopenia also occurs in patients suffering from malnutrition, congestive heart failure, chronic obstructive pulmonary disease, chronic renal failure, etc. [23]. Therefore, we cannot exclude the possibility that such potential confounders could have also increased sarcopenia in our patients and influenced cancer recurrence. Third, the definition of sarcopenia varies depending on different studies. Two main diagnostic tools have been proposed for sarcopenia; one used muscle mass only, as reported by Prado et al. in 2008 [29], and one used the presence of low gate speed, decreased grip strength, and low muscle mass, as reported by the European Working Group on Sarcopenia in 2010 [23]. In our study, we used muscle mass to define sarcopenia, because many studies have used this definition in predicting post-operative outcomes in NSCLC patients. Furthermore, we used original cut-off values to define sarcopenia. Therefore, the findings may not be generalized to other cut-off values or cohorts. To address this issue, we analyzed the prognosis using our cut-off values in the validation cohort; this may be considered plausible. Finally, LMR values may vary over time; therefore, we routinely collected the hematological data from each patient within the two weeks before surgical treatment. However, using only one set of hematological data may not offer adequate precision for assessing post-operative prognosis.

Conclusion

In this study, sarcopenia was a risk indicator for post-operative recurrence in patients with NSCLC. Our findings indicate the need for future translational research to clarify the biological interaction between sarcopenia and regulation of cancer immunity.

Supporting information

S1 Fig. ROC curve for predicting recurrence using sarcopenia.

ROC, receiver operating characteristic.

(TIF)

Click here for additional data file. (46KB, tif)
S2 Fig. OS and DFS after surgery compared between sarcopenia patients and non-sarcopenia patients in the validation cohort.

DFS, disease-free survival; OS, overall survival.

(TIF)

Click here for additional data file. (44.6KB, tif)
S3 Fig. CIR rate after surgery between sarcopenia patients and non-sarcopenia patients in the validation cohort.

CIR, cumulative incidence of recurrence.

(TIF)

Click here for additional data file. (29.8KB, tif)
S1 Dataset. Data set used in this study.

(XLSX)

Click here for additional data file. (91.7KB, xlsx)

Data Availability

All relevant data are within the manuscript and its Supporting information files.

Funding Statement

The authors received no specific funding for this work.

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Decision Letter 0

Amir Radfar

7 Jun 2021

PONE-D-21-05704

Sarcopenia increases the risk of post-operative recurrence in patients with non-small cell lung cancer

PLOS ONE

Dear Dr. Kawaguchi,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Specifically:

  •   Please elaborate on comments made by reviewer # 1.

  •   Please make sure to address all  confounding factors that may affect the conclusion.

Please submit your revised manuscript by Jul 18 2021 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

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We look forward to receiving your revised manuscript.

Kind regards,

Amir Radfar, MD,MPH,MSc,DHSc

Academic Editor

PLOS ONE

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Reviewers' comments:

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Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: No

Reviewer #2: Yes

Reviewer #3: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: No

Reviewer #2: Yes

Reviewer #3: Yes

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Correlation does not necessarily imply causation, and P-value does not take this confounding into account.

In this study, the relationship between sarcopenia and the prognosis of patients with NSCLC seems to be associative, not causative. The authors failed to demonstrate the causation.

Besides, the adjustment for the important confounders is ignored, for example, adjuvant treatments (that are usually indicated for patients with Stage 2-3 NSCLC [according to the ESMO and NCCN guidelines]), smoking (that increase the rate of recurrence [DOI: 10.1183/13993003.congress-2016.PA4339] and impairs the survival [DOI: 10.1186/s12885-020-07358-3], tumor size, and nodal size [DOI: 10.1016/j.radonc.2020.07.030]. In addition, the investigators have not entered the age -as a confounding factor- to the multivariate analysis, while the mean age of patients with sarcopenia was significantly higher than others.

It seems that the investigators have tried to demonstrate the causative inference between sarcopenia and the prognosis in NSCLC -exclusively- using mathematical models. However, the causative connection is rather loose.

Reviewer #2: (I) Summary

The authors of this manuscript look into the role of sarcopenia and post-operative reccurence in NSCLC.

In a retrospective series of 256 treated patients with lobectomy and LN dissection at a single institution during a 5y span they explore the prognostic role of preoperative sarcopenia. Using a Cox`s model they provide they provide evidence of patients being at higher risk for recurrence if having sarcopenia preoperatively (HR 2.38, p=.001).

They acknowledge limitations of their work (retrospective study, no standard definition for sarcopenia) and propose future research to clarify effect of sarcopenia in cancer.

(II) Discussion of specific areas of improvement

1.) Abstract

2.) Introduction,

- line 49: reference?

3.) Materials and methods

- line 83: was any software used to assess muscle area?

- line 87: cut-off for sarcopenia was derived on the same population as it was tested on for recurrence. This is problematic and should be pointed-out in the discussion section! Additional analysis with cut-off values from standardised groups (normal population) could mitigate this problem.

4.) Results

5.) Discussion

- line 209: no set standard cut-off values for sarcopenia should be added as important limitation as other cut-offs could dramatically change results of this study!

(III) Other comments

- The discussion section, in general, could be a little more structured, but all in all a nice article to read.

- clear and informative tables and charts.

Reviewer #3: Dear Authors:

Thank you for submitting your interesting work. I do highlight the potential impact for interventional strategies in order to cope with sarcopenia in NSCLC patients such as exercise, which has shown important recurrence risk reductions in other cancer sites at different disease stages.

I would suggest to take precautions on assigning causality relationship between sarcopenia and post-operative recurrence risk in NSCLC patients taken from an observational retrospective study. You have made efforts to handle confounding risk but this should be explained and controlled thoroughly in the multivariate analysis and the discussion section in order to appropriately assign causality conclusions. Please consider revising Causality criteria available at ESMO Handbook of Interpreting Oncological Study Publications for this matter.

**********

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Reviewer #1: Yes: Farzad Taghizadeh-Hesary

Reviewer #2: No

Reviewer #3: Yes: Andrés M Acevedo

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PLoS One. 2021 Sep 22;16(9):e0257594. doi: 10.1371/journal.pone.0257594.r002

Author response to Decision Letter 0

6 Jul 2021

Responses to the comments from the Editor and reviewers

Editor

We would like to thank the Editor for the constructive critique that helped us improve the manuscript. We have made every effort to address the issues raised and to respond to all the comments. The text revised in response to the comments has been indicated by red font in the revised manuscript. Our detailed, point-by-point responses to the comments are provided below.

Please elaborate on comments made by reviewer # 1.

Response: We have revised our manuscript as suggested by reviewer # 1, and have responded to each of the comments individually.

Please make sure to address all confounding factors that may affect the conclusion.

Response: As suggested, we have addressed all confounding factors that could have affected the conclusion in both, Table 2 (univariate analysis) and Table 3 (multivariate analysis).

Journal Requirements:

When submitting your revision, we need you to address these additional requirements.

1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at

https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and

https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf

Response: As suggested, we have revised our manuscript based on the style requirements of PLOS ONE.

2. In the ethics statement in the manuscript and in the online submission form, please provide additional information about the patient records/samples used in your retrospective study, including: a) whether all data were fully anonymized before you accessed them; b) the date range (month and year) during which patients' medical records/samples were accessed.

Response: As suggested, we added the following information in the Methods section and in the online submission form:

“We accessed patients’ medical records between April 2020 and June 2021. These records were all anonymized during data collection; we used the anonymized data for our analysis.”

3. PLOS requires an ORCID iD for the corresponding author in Editorial Manager on papers submitted after December 6th, 2016. Please ensure that you have an ORCID iD and that it is validated in Editorial Manager. To do this, go to ‘Update my Information’ (in the upper left-hand corner of the main menu), and click on the Fetch/Validate link next to the ORCID field. This will take you to the ORCID site and allow you to create a new iD or authenticate a pre-existing iD in Editorial Manager. Please see the following video for instructions on linking an ORCID iD to your Editorial Manager account: https://www.youtube.com/watch?v=_xcclfuvtxQ

Response: The corresponding author has an ORCID iDs, but the following alert appears on entering the iD and password: “An identical, validated ORCID already exists in the database.”

4.Thank you for stating the following financial disclosure:

"The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript."

At this time, please address the following queries:

a. Please clarify the sources of funding (financial or material support) for your study. List the grants or organizations that supported your study, including funding received from your institution.

b. State what role the funders took in the study. If the funders had no role in your study, please state: “The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.”

c. If any authors received a salary from any of your funders, please state which authors and which funders.

d. If you did not receive any funding for this study, please state: “The authors received no specific funding for this work.”

Response: The authors received no specific funding for this work. This has been specified in the cover letter as suggested.

Please include your amended statements within your cover letter; we will change the online submission form on your behalf.

5. Review Comments to the Author

The authors would like to thank the reviewers for the constructive critique, which has helped to improve the manuscript. We have made every effort to address the issues raised and to respond to all the comments. The text revised in response to the comments has been indicated by red font in the revised manuscript. Our detailed, point-by-point responses to the comments are provided below.

Reviewer #1: Correlation does not necessarily imply causation, and P-value does not take this confounding into account.

In this study, the relationship between sarcopenia and the prognosis of patients with NSCLC seems to be associative, not causative. The authors failed to demonstrate the causation.

Besides, the adjustment for the important confounders is ignored, for example, adjuvant treatments (that are usually indicated for patients with Stage 2-3 NSCLC [according to the ESMO and NCCN guidelines]), smoking (that increase the rate of recurrence [DOI: 10.1183/13993003.congress-2016.PA4339] and impairs the survival [DOI: 10.1186/s12885-020-07358-3], tumor size, and nodal size [DOI: 10.1016/j.radonc.2020.07.030]. In addition, the investigators have not entered the age -as a confounding factor- to the multivariate analysis, while the mean age of patients with sarcopenia was significantly higher than others.

Response: We sincerely appreciate your observations and would like to thank you suggesting the relevant studies.

Based on your observations, we have added these confounders, namely, age, performance status, smoking history, adjuvant treatment, tumor size, and lymph node size to Tables 2 and 3. As a result, the HR or P value have changed slightly; nevertheless, the independent risk factors for post-operative recurrence remained the same. We believe that adding these factors would make our results more convincing to the readers.

It seems that the investigators have tried to demonstrate the causative inference between sarcopenia and the prognosis in NSCLC -exclusively- using mathematical models. However, the causative connection is rather loose.

Response: We appreciate your observations.

We have checked the causality criteria in the ESMO Handbook, and concluded that our results only demonstrated the relationship between sarcopenia and post-operative recurrence; they did not demonstrate causation, as the causality criteria were not fulfilled in this study.

We therefore deleted the sentence: “Sarcopenia increased the risk of post-operative recurrence in patients with NSCLC” from the conclusion, which have been revised as follows:

“Sarcopenia was the risk indicator for post-operative recurrence in patients with NSCLC. Our findings indicate the need for future translational research to clarify the biological interaction between sarcopenia and regulation of cancer immunity.”

Reviewer #2: (I) Summary

The authors of this manuscript look into the role of sarcopenia and post-operative reccurence in NSCLC.

In a retrospective series of 256 treated patients with lobectomy and LN dissection at a single institution during a 5y span they explore the prognostic role of preoperative sarcopenia. Using a Cox`s model they provide they provide evidence of patients being at higher risk for recurrence if having sarcopenia preoperatively (HR 2.38, p=.001).

They acknowledge limitations of their work (retrospective study, no standard definition for sarcopenia) and propose future research to clarify effect of sarcopenia in cancer.

(II) Discussion of specific areas of improvement

1.) Abstract

2.) Introduction,

- line 49: reference?

Response: We apologize for the error, and have added the citation accordingly (reference number [9]).

3.) Materials and methods

- line 83: was any software used to assess muscle area?

Response: We used Shade Quest View R (Fujifilm, Japan) software to assess muscle area.

The relevant text has been revised in the Methods; the revised text reads:

“The cross-sectional areas (cm2) of the right and left psoas muscles at the L3 level were measured by manual tracing of CT data using Shade Quest View R (Fujifilm, Japan).”

- line 87: cut-off for sarcopenia was derived on the same population as it was tested on for recurrence. This is problematic and should be pointed-out in the discussion section! Additional analysis with cut-off values from standardised groups (normal population) could mitigate this problem.

Response: We sincerely appreciate your observations and suggestion.

As suggested, we performed additional analysis using cut-off values from standardized groups, in which patients received surgery in 2016 and were observed up to 2021 (5 years); we believe that this will make our original cut-off values more plausible.

We added the following text to the Methods:

“In addition, we created another group which included patients who underwent curative lobectomy and lymph node dissection for NSCLC at our institution in 2016; this was the validation cohort. In this cohort, we analyzed the association between sarcopenia and post-operative recurrence using our PMI cut off values, and assessed the plausibility.”

We have also added the following text to the Results:

“To assess the plausibility of our original PMI cut off values, we analyzed prognosis using the validation cohort, which included 36 sarcopenia and 46 non-sarcopenia patients. The 5-year OS and DFS after surgery were 77.9% and 50.2%, respectively, in patients with sarcopenia versus 88.0% and 66.5%, respectively, in patients without sarcopenia (S2 Fig). The 5-year CIR rate was 48.0% in patients with sarcopenia versus 29.3% in patients without sarcopenia (S3 Fig). Based on these results, we considered our PMI cut off values to be plausible, as we could demonstrate the association between sarcopenia and post-operative recurrence in the validation cohort.”

This is problematic and should be pointed-out in the discussion section.

Response: As correctly observed, the lack of set standard cut-off values for sarcopenia was an important limitation.

We have therefore added the following text to the Discussion:

“Furthermore, we used original cut-off values to define sarcopenia. Therefore, the findings may not be generalized to other cut-off values or cohorts. To address this issue, we analyzed the prognosis using our cut-off values in the validation cohort; this may be considered plausible.”

4.) Results

5.) Discussion

- line 209: no set standard cut-off values for sarcopenia should be added as important limitation as other cut-offs could dramatically change results of this study!

Response: As correctly observed, the lack of set standard cut-off values for sarcopenia was an important limitation.

We have therefore added the following text to the Discussion:

“Furthermore, we used original cut-off values to define sarcopenia. Therefore, the findings may not be generalized to other cut-off values or cohorts. To address this issue, we analyzed the prognosis using our cut-off values in the validation cohort; this may be considered plausible.”

(III) Other comments

- The discussion section, in general, could be a little more structured, but all in all a nice article to read.

Response: We appreciate your observations, and have accordingly restructured the Discussion section; the text has been divided into to 5 paragraphs instead of 4, and the first sentences of each paragraph have been revised to improve clarity.

- clear and informative tables and charts.

Response: We appreciate your careful appraisal.

Reviewer #3: Dear Authors:

Thank you for submitting your interesting work. I do highlight the potential impact for interventional strategies in order to cope with sarcopenia in NSCLC patients such as exercise, which has shown important recurrence risk reductions in other cancer sites at different disease stages.

I would suggest to take precautions on assigning causality relationship between sarcopenia and post-operative recurrence risk in NSCLC patients taken from an observational retrospective study. You have made efforts to handle confounding risk but this should be explained and controlled thoroughly in the multivariate analysis and the discussion section in order to appropriately assign causality conclusions. Please consider revising Causality criteria available at ESMO Handbook of Interpreting Oncological Study Publications for this matter.

Response: We appreciate your observations.

We have checked the causality criteria in the ESMO Handbook, and concluded that our results only demonstrated the relationship between sarcopenia and post-operative recurrence; they did not demonstrate causation, as the causality criteria were not fulfilled in this study.

We therefore deleted the sentence: “Sarcopenia increased the risk of post-operative recurrence in patients with NSCLC” from the conclusion, which have been revised as follows:

“In this study, sarcopenia was a risk indicator for post-operative recurrence in patients with NSCLC. Our findings indicate the need for future translational research to clarify the biological interaction between sarcopenia and regulation of cancer immunity.”

Decision Letter 1

Amir Radfar

27 Jul 2021

PONE-D-21-05704R1

Sarcopenia increases the risk of post-operative recurrence in patients with non-small cell lung cancer

PLOS ONE

Dear Dr. Kawaguchi,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Specifically, please address comments made by reviewer #3

Please submit your revised manuscript by Sep 10 2021 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

  • A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.

  • A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.

  • An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Amir Radfar, MD,MPH,MSc,DHSc

Academic Editor

PLOS ONE

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

Additional Editor Comments (if provided):

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

Reviewer #3: (No Response)

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: No

Reviewer #2: Yes

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: In this retrospective study, authors have delineated the association between sarcopenia and risk of post-operative recurrence in patients with non-small cell lung cancer. The authors accomplished to address all the comments.

Reviewer #2: Manuscipt “Sarcopenia increases the risk of post-operative recurrence in patients with non-small cell lung cancer”

Reviewer #2, 2nd review

The authors have corrected issues addressed in my initial review as well as issues pointed out by other reviewers.

To make the connection between sarcopenia and recurrence more plausible they have added a validation cohort from patients treated at the same institution but at a different time point. While having a validation cohort is an excellent idea, more could be gained if the cohort would be more independent (other institution, region, country…), but this would make the project much bigger.

They acknowledge the limitations of their study in the discussion section, which is now clearly structured, and provide a revised conclusion taking into account the issue of correlation / causation.

At this point I have no other issues / suggestions regarding this paper.

Reviewer #3: Dear Authors:

Thank you for providing a new version of your manuscript. I have noticed that you addressed major confounding bias by statistical means. This clarifies the interpretation that the reader can have based on your results.

I have the following minor concerns to be addressed in the final manuscript if it is to be published:

Introduction, line 50: If the statement refers to any evidence published or any own work, please provide reference accordingly.

As PLOSOne is not a Clinical cancer exclusive journal, please consider explaining disease burden that makes your research relevant.

Methods, lines 101 onwards: please indicate primary variable for statistical analysis according to the objective of the study (line 56) to prevent spurious P-value interpretation.

Results: Table 1. Please provide characterization of variables to be included in the multivariate analysis, especially Psoas muscle mass index as independent risk factor.

Discussion: Exercise is a potential intervention that could affect muscle mass, but it is not solely as should be part of multimodal intervention strategies such as nutritional assessment and treatment. Please discuss if other potential confounders increasing sarcopenia and recurrence risk relationship were not included in your study.

**********

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Reviewer #1: Yes: Farzad Taghizadeh-Hesary

Reviewer #2: No

Reviewer #3: Yes: Andres M. Acevedo

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

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PLoS One. 2021 Sep 22;16(9):e0257594. doi: 10.1371/journal.pone.0257594.r004

Author response to Decision Letter 1

10 Aug 2021

Responses to the comments from the Editor and reviewers

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

Response: Thank you for this comment. We have reviewed the reference list and ensured that it is complete. None of the papers cited in our article have been retracted.

Reviewer #1: In this retrospective study, authors have delineated the association between sarcopenia and risk of post-operative recurrence in patients with non-small cell lung cancer. The authors accomplished to address all the comments.

Response: We would like to thank Reviewer #1 for their valuable advice that has helped us improve our manuscript.

Reviewer #2: Manuscipt “Sarcopenia increases the risk of post-operative recurrence in patients with non-small cell lung cancer”

The authors have corrected issues addressed in my initial review as well as issues pointed out by other reviewers.

To make the connection between sarcopenia and recurrence more plausible they have added a validation cohort from patients treated at the same institution but at a different time point. While having a validation cohort is an excellent idea, more could be gained if the cohort would be more independent (other institution, region, country…), but this would make the project much bigger.

They acknowledge the limitations of their study in the discussion section, which is now clearly structured, and provide a revised conclusion taking into account the issue of correlation / causation.

At this point I have no other issues / suggestions regarding this paper.

Response: We would like to thank Reviewer #2 for their pertinent advice that has helped to improve our manuscript.

Reviewer #3: Dear Authors:

Thank you for providing a new version of your manuscript. I have noticed that you addressed major confounding bias by statistical means. This clarifies the interpretation that the reader can have based on your results.

Response: We would like to thank Reviewer #3 for the constructive critique, which has helped improve the manuscript.

I have the following minor concerns to be addressed in the final manuscript if it is to be published:

Response: The revised text in response to the comments from Reviewer #3 is indicated in blue font in the revised manuscript. Our detailed, point-by-point responses to the comments are provided below.

Introduction, line 50: If the statement refers to any evidence published or any own work, please provide reference accordingly.

Response: Thank you for this comment. As suggested, we have included our previously published work under reference [9].

[10] Kawaguchi Y, Hanaoka J, Ohshio Y, Okamoto K, Kaku R, Hayashi K, et al. Does sarcopenia affect postoperative short- and long-term outcomes in patients with lung cancer?-a systematic review and meta-analysis. J Thorac Dis. 2021;13(3):1358-69. doi: 10.21037/jtd-20-3072. PubMed PMID: 33841929; PubMed Central PMCID: PMCPMC8024851. As PLOSOne is not a Clinical cancer exclusive journal, please consider explaining disease burden that makes your research relevant.

Response: Thank you for your advice. We have added some general information on NSCLC and cancer-related sarcopenia to the Introduction.

Page 3, lines 42-45:

“Non-small cell lung cancer (NSCLC) is a major cause of cancer-related deaths globally [1]. Although tumor characteristics, such as histology and TNM stage, and treatment factors, such as surgery and chemotherapy, have traditionally been considered important to determine cancer prognosis, recently, patient factors like sarcopenia have started gaining attention [2]. ”

Methods, lines 101 onwards: please indicate primary variable for statistical analysis according to the objective of the study (line 56) to prevent spurious P-value interpretation.

Response: Thank you for this comment. Accordingly, we have specified that CIR was the primary variable in the Methods section:

Page 6, lines 108-109:

“CIR was defined as the interval between the date of surgery and the date of cancer recurrence (confirmed using an imaging test) and was set as the primary variable.”

Results: Table 1. Please provide characterization of variables to be included in the multivariate analysis, especially Psoas muscle mass index as independent risk factor.

Response: Thank you for this suggestion. We have now provided all variables used in the multivariate analysis, including psoas mass index, in Table 1. Furthermore, following additional analysis, we found that NSCLC patients with sarcopenia can experience more malignant disease than those without sarcopenia. We have added this information to the Discussion of the revised manuscript.

Page 15, lines 202-203:

“In the present study, NSCLC patients with sarcopenia presented with larger tumor size, larger lymph node size, and more vascular invasion than those without sarcopenia.”

Discussion: Exercise is a potential intervention that could affect muscle mass, but it is not solely as should be part of multimodal intervention strategies such as nutritional assessment and treatment. Please discuss if other potential confounders increasing sarcopenia and recurrence risk relationship were not included in your study.

Response: Thank you for this pertinent comment. Reviewer #1 also mentioned that other potential confounders might increase sarcopenia and cancer recurrence. We have therefore added this information to the section on limitations in the Discussion of the revised manuscript.

Page 17, lines 230-233:

“Second, sarcopenia also occurs in patients suffering from malnutrition, congestive heart failure, chronic obstructive pulmonary disease, chronic renal failure, etc. [23]. Therefore, we cannot exclude the possibility that such potential confounders could have also increased sarcopenia in our patients and influenced cancer recurrence.”

Attachment

Submitted filename: (R2 subumission) Respons to Reviewers.docx

Click here for additional data file. (25.8KB, docx)

Decision Letter 2

Amir Radfar

7 Sep 2021

Sarcopenia increases the risk of post-operative recurrence in patients with non-small cell lung cancer

PONE-D-21-05704R2

Dear Dr. Kawaguchi,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Amir Radfar, MD,MPH,MSc,DHSc

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #3: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

Reviewer #3: Yes

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #3: Yes

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4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #3: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #3: Yes

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6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The authors have addressed all the comments.

There is no additional comment.

Reviewer #3: Thank you for updating your manuscript. I have no further comments or revisions to make at this point.

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #3: Yes: Andrés M Acevedo M

Acceptance letter

Amir Radfar

14 Sep 2021

PONE-D-21-05704R2

Sarcopenia increases the risk of post-operative recurrence in patients with non-small cell lung cancer

Dear Dr. Kawaguchi:

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org.

If we can help with anything else, please email us at plosone@plos.org.

Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Dr. Amir Radfar

Academic Editor

PLOS ONE

Associated Data

    This section collects any data citations, data availability statements, or supplementary materials included in this article.

    Supplementary Materials

    S1 Fig. ROC curve for predicting recurrence using sarcopenia.

    ROC, receiver operating characteristic.

    (TIF)

    Click here for additional data file. (46KB, tif)
    S2 Fig. OS and DFS after surgery compared between sarcopenia patients and non-sarcopenia patients in the validation cohort.

    DFS, disease-free survival; OS, overall survival.

    (TIF)

    Click here for additional data file. (44.6KB, tif)
    S3 Fig. CIR rate after surgery between sarcopenia patients and non-sarcopenia patients in the validation cohort.

    CIR, cumulative incidence of recurrence.

    (TIF)

    Click here for additional data file. (29.8KB, tif)
    S1 Dataset. Data set used in this study.

    (XLSX)

    Click here for additional data file. (91.7KB, xlsx)
    Attachment

    Submitted filename: (R2 subumission) Respons to Reviewers.docx

    Click here for additional data file. (25.8KB, docx)

    Data Availability Statement

    All relevant data are within the manuscript and its Supporting information files.

    Articles from PLoS ONE are provided here courtesy of PLOS

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