Abstract
Objectives
The clinical decision-making regarding post hoc management of early colorectal cancer (CRC) patients who have undergone non-curative endoscopic resection (ER) remains a subject of debate. This systematic review and meta-analysis aims to compare the clinical outcomes between patients undergoing additional surgery and those receiving surveillance only.
Methods
A comprehensive literature search was conducted across three major medical databases: PubMed, Embase, and the Cochrane Library. STATA software was utilized for pooling analysis. The methodological quality of the included studies was assessed using the Newcastle–Ottawa Quality Scale.
Results
A total of 15 eligible studies encompassing 3,508 early CRC patients were included in this meta-analysis (additional surgery group: 1,974 cases; surveillance-only group: 1,533 cases). All included studies demonstrated good methodological quality, with Newcastle–Ottawa scores no less than 6. The results of the meta-analysis indicated that compared to the surveillance-only group, patients in the additional surgery group exhibited significantly improved overall survival (OR = 2.95, 95% CI: 2.05–4.24, P < 0.05), enhanced recurrence-free survival (OR = 2.53, 95% CI = 1.38–4.62, P < 0.05), a reduced recurrence rate (OR = 1.96, 95% CI = 1.22–3.13, P < 0.05), and a lower local recurrence rate (OR = 2.35, 95% CI = 1.12–4.95, P < 0.05). No significant sources of heterogeneity were identified among the studies analyzed; publication bias was also deemed acceptable across these investigations. Furthermore, we performed subgroup analyses based on inclusion criteria and age stratification which revealed notable differences in effect sizes between groups (JSCCR subgroup: OR = 2.09; 95% CI = 1.32–3.30 versus Non-JSCCR subgroup: OR = 1 .54; 95% CI = 0.89 -2.65, indicating negative results). Pooling analysis showed no significant difference between subgroups when stratified by age using a cutoff value of 65 years old.
Conclusions
Compared to patients who underwent surveillance only, those receiving additional surgical treatment demonstrated superior outcomes in terms of overall survival, recurrence-free survival, recurrence rates, and control of local recurrences. This suggests that such an approach may represent a more optimal clinical decision for early-stage colorectal cancer (CRC) patients who have received non-curative endoscopic resection (ER). Furthermore, this study indicates that the inclusion criteria significantly influence the reported outcomes. Notably, age did not affect the recurrence rate. Overall, this is the first meta-analysis aimed at exploring and clarifying this ongoing controversy.
Supplementary Information
The online version contains supplementary material available at 10.1186/s12876-024-03502-6.
Keywords: Early colorectal cancer, Additional surgery, Surveillance-only, Overall survival, Recurrence, Meta-analysis
Introduction
Colorectal cancer (CRC) is among the most prevalent malignancies of the digestive tract globally, particularly in developing nations such as China [1, 2]. According to the GLOBOCAN report, both the incidence and mortality rates of CRC are on a continuous rise, positioning it as one of the three most commonly diagnosed cancers. It is estimated that there are 1.9 million new cases annually, along with approximately 935,000 deaths each year [3].
The implementation of nationwide CRC screening programs and advancements in endoscopic screening techniques have led to an increase in early-stage CRC detections and a reduction in mortality rates among CRC patients [4, 5]. Early-stage CRC patients, including those with T1 CRC, have demonstrated remarkably favorable outcomes, with five-year overall survival rates exceeding 90% [6]. The majority of these patients undergo treatment through curative endoscopic resection (ER) or radical surgery.
However, there remains a significant number of patients who have not undergone curative endoscopic resection (ER) or radical surgical intervention. Residual tumor cells may persist following non-curative or localized endoscopic resections in these individuals. For patients with non-curative ER, it is imperative to conduct regular clinical evaluations and consider further invasive treatments, such as additional surgery. For patients diagnosed with high-risk early-stage colorectal cancer, there are specific circumstances that may warrant additional surgical intervention. These include the presence of adverse pathological features, suspicious positive margins, and a heightened risk of lymph node metastasis [7, 8].
Shallow infiltrating cancer that invades the submucosal layer may be considered for ER. Prior to making a decision regarding endoscopic resection, it is essential to conduct a thorough evaluation of pertinent factors such as tumor size, anticipated depth of infiltration, and degree of differentiation. For cases where preoperative endoscopic ultrasound examination indicates T1 stage or postoperative pathology confirms T1 stage following local excision, if the tumor has been completely removed with negative margins (including at the base) and exhibits favorable prognostic histological characteristics (such as well-differentiated status and absence of vascular invasion), additional surgical resection is not recommended, regardless of whether the tumor is broad-based or pedunculated. Conversely, in instances where poor prognostic histological features are present or there has been incomplete removal with an inability to assess specimen fragmentation margins, additional segmental bowel resection along with regional lymph node dissection is advised. However, these experiences regarding the difficulties clinicians face in deciding between additional surgery and surveillance-only strategies for ER patients still lacked substantial evidence to support them.
In clinical practice, the optimal strategy for subsequent treatment remains a subject of debate. Consequently, this study aims to perform the first systematic review and meta-analysis comparing long-term outcomes between additional surgical interventions and surveillance-only strategies for early colorectal cancer (CRC) patients following non-curative ER.
Methods
The present study was conducted in accordance with the Meta-analyses of Observational Studies in Epidemiology (MOOSE) guidelines [9] (refer to Supplementary Table 1) and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement [10] (refer to Supplementary Table 2).
Medical databases and search strategy
Comprehensively, three primary medical databases were systematically searched: PubMed, Embase, and the Cochrane Library. This search encompassed publications from their inception up to May 9th, 2024. A combination of Medical Subject Headings (MeSH) and relevant free-text terms related to ‘colorectal cancer,’ ‘endoscopic resection,’ ‘additional surgery,’ and ‘surveillance’ was employed for literature retrieval, with no restrictions imposed on language, region, country, or ethnicity.
Literature selection criteria and outcome measures
The present study encompassed research that reported outcomes for patients with colorectal cancer (CRC) who underwent non-curative endoscopic resection and subsequently received either additional surgical intervention or surveillance alone. Publications involving non-human subjects, in vitro studies, case reports, case series, reviews, irrelevant topics, or those lacking sufficient data were excluded following a thorough screening of titles/abstracts or full-text literature review. In instances where two publications presented overlapping data, the study with the larger sample size and/or longer duration was selected.
Non-curative endoscopic resection is defined by the Japanese Society for Cancer of the Colon and Rectum (JSCCR) [11] as follows:
-
(I)
Presence of horizontal or vertical positive resection margins;
-
(II)
Submucosal invasion exceeding 1,000 μm;
-
(III)
Poor differentiation;
-
(IV)
Lymphovascular infiltration;
-
(V)
Perineural invasion;
-
(VI)
Tumor budding.
The indications for endoscopic resection as defined by the JSCCR are as follows:
Superficial or early submucosal invasive carcinoma of the mucosa;
Size remains unaffected;
Applicable to any histological type.
Additional surgical guidelines established by the JSCCR are outlined below:
Following endoscopic resection, it is imperative to perform a comprehensive histological examination of the specimen to evaluate the completeness of the endoscopic treatment and ascertain whether further interventions are necessary. This process includes: (1) marking the resection margins of polyp specimens with indelible dye or other markers to ensure visibility of all sections, including these margins; (2) meticulously stretching and fixing both EMR and ESD specimens in order to prepare a vertical section that is perpendicular to the muscularis mucosae.
The primary outcome measures included overall survival (OS) and recurrence rate. The secondary outcome measures comprised disease-free survival (DFS), disease-specific survival (DSS), recurrence-free survival (RFS), local recurrence rate (LR), and rates of distant metastasis or lymph node involvement.
Data extraction and methodological quality assessment
Excel forms were utilized for data extraction. The study gathered information encompassing the author’s name, publication year, language of publication, duration of the study, patient age, patient gender, inclusion criteria for endoscopic therapy, and all aforementioned outcome measurements.
The methodological quality of the included publications was assessed using the Newcastle–Ottawa Scale, which allocates a maximum quality score of 9 points [12].
Statistical methods
Odds ratios (OR) with 95% confidence intervals (CI) were utilized as effect sizes for the meta-analysis. An OR greater than 1 is considered unfavorable data for the experimental group. Risk estimates from the included studies were analyzed using DerSimonian-Laird random-effects models. Heterogeneity was assessed through the Chi-square test and I2-statistic. An I2 value of 0–25% indicates insignificant heterogeneity, 26–50% reflects low heterogeneity, 51–75% denotes moderate heterogeneity, and values exceeding 75% signify high heterogeneity [13, 14]. Sensitivity analysis was conducted to identify potential sources of heterogeneity. Furthermore, funnel plots and Egger’s test were employed to evaluate publication bias across the studies [15]. Statistical analyses were performed using STATA version 26.0, with a two-tailed P-value < 0.05 indicating statistical significance.
Results
Literature selection process
The initial search yielded a total of 1,974 articles from three primary medical databases: PubMed (1,562 articles), Embase (667 articles), and the Cochrane Library (78 articles). After eliminating overlapping and irrelevant studies, 49 articles were selected for full-text review. Ultimately, 15 eligible articles [16–30] were included in this meta-analysis. A detailed flow diagram is presented in Fig. 1.
Fig. 1.
Flow diagram of included studies
Study characteristics
As presented in Table 1, this meta-analysis ultimately included a total of 15 publications encompassing 3,508 early-stage colorectal cancer (CRC) patients. The additional surgery group comprised 1,974 cases, while the surveillance-only group consisted of 1,533 cases. The publication years ranged from 2014 to 2024, with study periods extending from 1989 to 2019. All studies were published in English; notably, eight out of the fifteen studies focused on a Japanese population. Importantly, regarding patient inclusion criteria, eleven out of the fifteen studies utilized guidelines established by JSCCR. All studies included in this review employed retrospective, observational designs (Table 1).
Table 1.
Characteristics of included publications
| Study ID | Country | Language | Publication Year | Study Period | Sample size | Study designs | Inclusion criteria | ER + Additional surgery | ER + Surveillance-Only | Outcome Measures |
|---|---|---|---|---|---|---|---|---|---|---|
| Li Jiyun | China | English | 2021 | 2010–2019 | 180 | R&O | JSCCR | 85 | 95 | OS/DFS/DSS/Recurrence/Local Recurrence/Distant metastasis |
| Eun Young Park | Korea | English | 2020 | 2007–2017 | 171 | R&O | Non-JSCCR | 117 | 54 | OS/RFS/Recurrence |
| Yuzuru Tamaru | Japan | English | 2017 | 1992–2008 | 359 | R&O | JSCCR | 238 | 121 | OS/DFS/DSS/Recurrence/Local Recurrence/Distant metastasis |
| Naoki Asayama | Japan | English | 2015 | 1992–2008 | 151 | R&O | JSCCR | 106 | 45 | OS/Recurrence/Local Recurrence/Distant metastasis |
| Minoru Kato | Japan | English | 2021 | 2009–2019 | 147 | R&O | JSCCR | 60 | 87 | OS/DSS/Recurrence |
| Shibo Song | China | English | 2024 | 2011–2021 | 275 | R&O | JSCCR | 102 | 173 | OS/RFS |
| Hyun Jin Bae | Korea | English | 2023 | 2000–2015 | 107 | R&O | JSCCR | 72 | 35 | OS/RFS/Recurrence |
| Yusuke Yoda | Japan | English | 2013 | 2000–2007 | 302 | R&O | JSCCR | 196 | 106 | OS/RFS/Recurrence/Local Recurrence/Distant metastasis |
| Marco Spadaccini | Italy | English | 2022 | 2012–2019 | 207 | R&O | Non-JSCCR | 126 | 81 | OS/DSS/Recurrence |
| Félix Corre | France | English | 2024 | 2012–2019 | 197 | R&O | Non-JSCCR | 107 | 90 | OS/Recurrence/Distant metastasis |
| Kenta Iguchi | Japan | English | 2019 | 2008–2015 | 192 | R&O | JSCCR | 176 | 15 | OS/DSS/Recurrence |
| Yoshitaka Nishikawa | Japan | English | 2019 | 2005–2015 | 37 | R&O | JSCCR | 19 | 18 | OS/DSS/RFS/Recurrence |
| Belderbos | Netherlands | English | 2017 | 1995–2011 | 590 | R&O | Non-JSCCR | 220 | 370 | RFS/Recurrence/Local Recurrence/Distant metastasis |
| Nozawa | Japan | English | 2016 | 2006–2015 | 204 | R&O | JSCCR | 145 | 59 | DSS/RFS |
| Yoshii | Japan | English | 2014 | 1989–2008 | 389 | R&O | JSCCR | 205 | 184 | DSS/Recurrence/Local Recurrence/Distant metastasis |
OS Overall Survival, DFS Disease free survival, DSS Disease specific survival, RFS Recurrence free survival, JSCCR Japanese Society for Cancer of the Colon and Rectum, R&O Retrospective and observational study design, ER Endoscopic Resection
Methodological quality assessment
As presented in Table 2, all studies included in this review were evaluated for methodological quality. The scores on the Newcastle–Ottawa Scale (NOS) indicated that each study demonstrated a relatively high level of methodological rigor, with NOS scores not falling below six.
Table 2.
Evaluation of methodological qualities using Newcastle–Ottawa Scale (NOS)
| Study | Selection(0–4) | Comparability(0–2) | Outcome(0–3) | Total | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| REC | SNEC | AE | DO | SC | AF | AO | FU | AFU | ||
| Li Jiyun | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 7 |
| Eun Young Park | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 7 |
| Yuzuru Tamaru | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 7 |
| Naoki Asayama | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 7 |
| Minoru Kato | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 7 |
| Shibo Song | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 7 |
| Hyun Jin Bae | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 7 |
| Yusuke Yoda | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 7 |
| Marco Spadaccini | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 7 |
| Félix Corre | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 7 |
| Kenta Iguchi | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 7 |
| Yoshitaka Nishikawa | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 7 |
| Belderbos | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 7 |
| Nozawa | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 7 |
| Yoshii | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 7 |
“1”indicates that the cohort study has satisfied the item and “0” indicates the opposite direction
REC Representativeness of the exposed cohort, SNEC Selection of the non-exposed cohort, AE Ascertainment of exposure, DO Demonstration that outcome of interest was not present at start of study, SC Study controls for age, sex, AF Study controls for any additional factors (donor source, immunotherapy, etc.), AO Assessment of outcome, FU Follow-up long enough (36 M) for outcomes to occur, AFU Adequacy of follow-up of cohorts (≥ 90%)
Meta-analysis results and exploration of heterogeneity
Overall Survival (OS)
A total of twelve articles reported on overall survival (OS) outcomes, encompassing 2,392 patients (with 1,380 undergoing additional surgery and 1,012 in the surveillance-only group). The pooled results indicated that patients who underwent further surgical intervention achieved significantly better OS compared to those in the surveillance-only group (OR = 2.95, 95% CI: 2.05–4.24, P < 0.05; see Fig. 2A), with no observed heterogeneity across studies (I2 = 0%).
Fig. 2.
Results of meta-analysis and sensitivity analysis for overall survival
Subsequently, a subgroup analysis was conducted based on the duration of OS. The pooled results revealed consistent findings within subgroups categorized by a follow-up period of 3–4 years (five studies; N = 763; OR = 2.35, 95% CI: 1.13–4.92; P < 0.05; see Fig. 2B), exhibiting no heterogeneity (I2 = 0%), as well as within the subgroup for a follow-up period of five years (seven studies; N = 1,629; OR = 3.22, 95% CI: 1.91–5.42; P < 0.05; see Fig. 2C), which demonstrated insignificant heterogeneity (I2 = 23.9%).
Sensitivity analyses were performed to evaluate the stability of these findings and to explore potential sources of heterogeneity among studies. As illustrated in Fig. 2D, E, and F, no significant variations were detected across the included studies.
Disease specific survival (DSS)
A total of six studies reported outcomes related to disease specific survival (DSS), encompassing 1,148 cases of colorectal cancer (CRC) patients (Additional surgery: 604 cases; Surveillance-only: 504 cases). The pooled analysis indicated that there was no significant difference between the additional surgery group and the surveillance-only group (OR = 1.41, 95% CI = 0.79–2.51, P > 0.05, Fig. 3A), with negligible heterogeneity observed (I2 = 13.7%). Sensitivity analyses demonstrated that effect sizes across studies were stable, revealing no apparent sources of heterogeneity (Fig. 3B).
Fig. 3.
Results of meta-analysis and sensitivity analysis for disease-specific survival
Disease-free survival (DFS)
Only two studies reported outcomes related to disease-free survival (DFS), encompassing a total of 539 cases: 323 cases underwent additional surgery, while 216 cases were subjected to surveillance only. The analysis revealed no significant difference between the additional surgery group and the surveillance-only group (OR = 1.35, 95% CI = 0.55–3.34, P > 0.05, Fig. 4). Furthermore, there was no evidence of heterogeneity observed (I2 = 0%).
Fig. 4.
Results of meta-analysis for disease-free survival
Recurrence-free survival (RFS)
A total of seven studies reported on the outcomes of recurrence-free survival (RFS), encompassing 1,686 colorectal cancer (CRC) patients, with 785 cases in the additional surgery group and 901 cases in the surveillance-only group. Pooled results indicated that, compared to patients undergoing surveillance only, those who received additional surgical intervention demonstrated a significantly improved RFS (OR = 2.53, 95% CI = 1.38–4.62, P < 0.05; see Fig. 5A), exhibiting low heterogeneity (I2 = 34.9%). Sensitivity analysis identified the study by Belderbos et al. as a potential source of heterogeneity (see Fig. 5B). Following the exclusion of this study, heterogeneity was reduced to zero (see Fig. 5C).
Fig. 5.
Results of meta-analysis and sensitivity analysis for recurrence-free survival
Recurrence Rate (RR)
A total of 12 studies reported on recurrence rates, encompassing 2,821 cases of colorectal cancer (CRC) patients. Among these, there were 1,484 cases in the additional surgery group and 1,337 cases in the surveillance-only group. The pooled results indicated that patients who underwent additional surgery had a significantly lower recurrence rate compared to those in the surveillance-only group (OR = 1.96, 95% CI = 1.22–3.13, P < 0.05; see Fig. 6A), with low heterogeneity observed (I2 = 32.1%). Sensitivity analysis did not reveal any significant sources of heterogeneity (see Fig. 6B).
Fig. 6.
Results of meta-analysis and sensitivity analysis for recurrence rate
Local Recurrence Rate (LRR)
Notably, the definition of “local recurrence” refers specifically to intramural recurrence and does not encompass cases that overlap with lymph node metastasis. There are six studies that report on the outcomes of local recurrence rates, encompassing a total of 1,971 cases of colorectal cancer (CRC) patients. Among these, there are 1,050 cases in the additional surgery group and 921 cases in the surveillance-only group. The pooled results indicate that compared to the surveillance-only group, patients in the additional surgery group exhibited a significantly lower local recurrence rate (OR = 2.35, 95% CI = 1.12–4.95, P < 0.05; see Fig. 7A), with low heterogeneity observed (I2 = 18.6%). Furthermore, sensitivity analysis revealed no apparent sources of heterogeneity (see Fig. 7B).
Fig. 7.
Results of meta-analysis and sensitivity analysis for local recurrence rate
Distant and lymph node metastasis rate
A total of seven studies reported outcomes related to the rates of distant metastasis and lymph node involvement, encompassing 2,168 cases of colorectal cancer (CRC) patients. This cohort included 1,067 patients who underwent additional surgical interventions and 1,101 patients who were subjected solely to surveillance. The pooled analysis indicated no significant difference in outcomes between those receiving additional surgery and those undergoing surveillance alone (OR = 0.92, 95% CI = 0.54–1.57, P > 0.05; see Fig. 8A), with an absence of heterogeneity observed (I2 = 0%). Furthermore, sensitivity analyses did not reveal any apparent sources of heterogeneity (see Fig. 8B).
Fig. 8.
Meta-analytical assessment of distal or lymphatic metastasis rate
Subgroup analysis based on inclusion criteria (JSCCR vs. Non-JSCCR)
In the subsequent subgroup analysis, we compared the endpoints of overall survival (OS) (Fig. 9A) and response rate (RR) between studies that included patients based on the Japan Society for Cancer of the Colon and Rectum (JSCCR) guidelines and those that did not include JSCCR patients. As illustrated in Fig. 9B, we observed a notable difference in effect sizes for RR between the two groups: JSCCR subgroup showed an odds ratio (OR) of 2.09 with a 95% confidence interval (CI) of 1.32–3.30, whereas the Non-JSCCR subgroup exhibited an OR of 1.54 with a 95% CI of 0.89–2.65, indicating negative results in this context. Consequently, these inclusion criteria significantly influenced the reported outcomes regarding recurrence rates.
Fig. 9.
Subgroup analysis based on inclusion criteria
Subgroup analysis of the elderly population and relatively younger population
Furthermore, we extracted age data for patients with recurrence and subsequently assessed the recurrence rates between two subgroups: those aged ≥ 65 years and those aged < 65 years. The pooled analysis indicated no significant difference in recurrence rates between these two age-stratified groups (cut-off value = 65 years), as demonstrated in Fig. 10 (RR = 0.80, 95% CI = 0.51–1.24, P > 0.05).
Fig. 10.
Subgroup analysis focused on the elderly population (relative ratio comparison)
Publication bias assessments
Funnel plots, accompanied by Egger’s test, were employed to assess publication bias across the studies, as illustrated in Fig. 11A-F. No significant publication bias was detected among the studies.
Fig. 11.
Funnel plots from egger’s tests
Discussion
This systematic review and meta-analysis represents the first comprehensive evaluation of clinical outcomes between patients with colorectal cancer (CRC) who underwent non-curative endoscopic resection (ER) and received additional surgery versus those who were managed with surveillance alone. The pooled results indicate that, compared to surveillance-only patients, individuals who underwent additional surgical intervention following non-curative ER experienced superior outcomes in terms of overall survival (OS), recurrence-free survival (RFS), recurrence rates, and local recurrence rates. Furthermore, all included studies demonstrated satisfactory Newcastle–Ottawa Scale (NOS) scores (all > 6), suggesting robust methodological quality. Notably, no significant sources of heterogeneity were identified.
In subgroup analyses, we observed that the inclusion criteria significantly influenced reported outcomes regarding recurrence rates. Specifically, within age stratification subgroups, there was no discernible difference in recurrence rates between older adults (≥ 65 years old) and their younger counterparts (< 65 years old). Additionally, publication bias across the studies was deemed acceptable.
To our knowledge, this study provides the first quantitative evidence to inform clinical decision-making regarding whether to pursue additional surgery or adopt a surveillance-only approach for CRC patients undergoing non-curative ER [31, 32].
In this meta-analysis, we designated OS and recurrence rate as primary endpoints due to their strong correlation with patient survival and prognosis. Concurrently, we established disease-specific survival (DSS), disease-free survival (DFS), RFS, local recurrences, as well as distant or lymphatic metastasis as secondary endpoints—each serving as valuable parameters for assessing patient outcomes. Moreover, we adhered to MOOSE and PRISMA guidelines along with NOS scales throughout this meta-analysis process; these frameworks underscore a rigorous methodology for our pooling analysis [33–35].
Apart from the robust endpoint settings and scientific methodologies employed in this meta-analysis, our findings also present an intriguing insight that may enhance clinical practice. In clinical settings, the subsequent decision-making process for early colorectal cancer (CRC) patients who have undergone non-curative endoscopic resection (ER) remains a contentious issue. This meta-analysis revealed significant differences between the additional surgery group and the surveillance-only group concerning overall survival (OS) and recurrence-free survival (RFS). The odds ratios (OR) for these two groups were found to be 2.95 for OS and 2.53 for RFS, indicating a markedly higher mortality risk among patients opting for surveillance alone after non-curative ER.
For the discrepancies observed between Disease-Free Survival (DFS) and Recurrence-Free Survival (RFS) results in relation to Overall Survival (OS) and recurrence rates, these variations may be attributed to differences in study design, follow-up durations, or patient characteristics across the included publications. There are three primary reasons for this as follows:
The inclusion criteria based on JSCCR guidelines may significantly influence outcomes related to recurrence rates;
Adherence to the JSCCR inclusion criteria could lead to improved outcomes concerning recurrence;
This indicates that compliance with specific guidelines enhances patient selection and overall treatment efficacy.
Further investigation through randomized controlled trials (RCTs) is warranted to explore these factors more comprehensively.
Limitations
We recognize that patients who did not undergo additional surgery may present with significant comorbidities, which complicates direct comparisons of overall survival rates between those who received supplementary surgical intervention and those who were monitored under surveillance alone. This concern represents the primary limitation of our study. Secondly, due to the involvement of only one reviewer, we address the potential bias in this meta-analysis.
Conclusions
Overall, this systematic review and meta-analysis demonstrated that, compared to patients receiving surveillance alone, additional surgical treatment yields superior outcomes in terms of overall survival, recurrence-free survival, recurrence rates, and control of local recurrences. This suggests that such an approach may represent a more optimal clinical decision for early-stage colorectal cancer (CRC) patients who have undergone non-curative endoscopic resection (ER). Furthermore, the study indicated that inclusion criteria significantly influence the reported outcomes; however, age did not appear to affect the recurrence rate.
In summary, this is the first meta-analysis aimed at exploring and clarifying this ongoing controversy.
Supplementary Information
Author’s contributions
Chun-zeng Jia conducted this whole project.
Funding
The author declare there is no funding.
Data availability
The datasets used and analyzed during the current study are available from the corresponding author upon reasonable request.
Declarations
Ethics approval and consent to participate
The formal ethical review was waived by our institutional review board.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Data Availability Statement
The datasets used and analyzed during the current study are available from the corresponding author upon reasonable request.