Abstract
Background
Incidences of esophageal cancer and obesity are both rising in the United States. The aim of this study was to determine the influence of elevated body mass index on outcomes after esophagectomy for cancer.
Methods
Overall and disease-free survivals in obese (BMI ≥ 30), overweight (BMI 25–29), and normal-weight (BMI 20–24) patients undergoing esophagectomy constituted the study end points. Survivals were calculated by the Kaplan–Meier method, and differences were analyzed by log rank method.
Results
The study included 166 obese, 176 overweight, and 148 normal-weight patients. These three groups were similar in terms of demographics and comorbidities, with the exception of younger age (62.5 vs. 66.2 vs. 65.3 years, P = 0.002), and higher incidence of diabetes (23.5 vs. 11.4 vs. 10.1%, P = 0.001) and hiatal hernia (28.3 vs. 14.8 vs. 20.3%, P = 0.01) in obese patients. Rates of adenocarcinoma histology were higher in obese patients (90.8 vs. 90.9 vs. 82.5%, P = 0.03). Despite similar preoperative stage, obese patients were less likely to receive neoadjuvant treatment (47.6 vs. 54.5 vs. 66.2%, P = 0.004). Response to neoadjuvant treatment, type of surgery performed, extent of lymphadenectomy, rate of R0 resections, perioperative complications, and administration of adjuvant chemotherapy were not influenced by BMI. At a median follow-up of 25 months, 5-year overall and disease-free survivals were longer in obese patients (respectively, 48, 41, 34%, P = 0.01 and 48, 44, 34%, P = 0.01).
Conclusions
In our experience, an elevated BMI did not reduce overall and disease-free survivals after esophagectomy for cancer.
The incidence of esophageal cancer in North America has been increasing in the recent years. In 2009, there were more than 16,000 new cases diagnosed in the United States and 14,530 deaths from disease.1 Although the explanation for this increase remains unclear, increasing epidemiologic evidence points to a direct correlation of obesity with gastroesophageal reflux disease and adenocarcinoma of the esophagus and esophagogastric junction.2–4
As obesity rises in our society, surgeons will be increasingly performing esophagectomies for cancer in obese patients. Surprisingly, the implications of obesity on outcomes in the management of esophageal cancer have not been systematically addressed. We aimed to study the influence of body mass index on perioperative and long-term results after esophagectomy for cancer. The primary end points for this study were overall survival (OS) and disease-free survival (DFS). The secondary end points were incidence of perioperative morbidity and mortality.
METHODS
In 2006, after institutional review board approval, the gastrointestinal department at Moffitt Cancer Center established a database of esophagectomy cases by performing a retrospective chart review of patients operated on at Moffitt Cancer Center between 1994 and 2008. The data collected for the database included patient demographics, preoperative symptoms, Charlson comorbidity index, risk factor history, family history, tumor stage and histopathologic features, perioperative events, and complications.5 Chart reviews were performed solely by experienced clinicians and were recorded on standardized abstraction forms. Data were entered into a secure Web-based data entry system and uploaded into an Access database by a data analyst. Ambiguities in any data points were discussed by the committee, researched, reviewed, and corrected. Currently 541 patient charts have been abstracted and are available for analysis.
All patients included in our study underwent staging with physical examination, esophagogastroduodenoscopy, endoscopic ultrasound, computed tomographic scans, computed tomographic/positron emission tomography or positron emission tomography scans, and cardiopulmonary clearance. The extent of esophageal resection (transthoracic, transhiatal, or three-field esophagectomy) and use of neoadjuvant therapy were determined by preoperative staging, multidisciplinary discussions, and surgeon preference. All pathology specimens taken during the initial endoscopic biopsies were assessed and confirmed by our pathologists before initiation of neoadjuvant therapy.
The database was queried to include all patients with recorded data on height and weight before surgery. Body mass index (BMI) was calculated according to a standardized definition as weight in kilograms divided by height in meters squared. We defined obesity according to the World Health Organization’s definition as BMI ≥ 30.6 We stratified patients into three BMI categories: obese (BMI ≥ 30), overweight (BMI 25–29), and normal weight (BMI 20–24). Patients considered malnourished at time of surgery (BMI < 20) were excluded. Variables analyzed included demographic data, intraoperative and postoperative outcomes, and survival data. For the demographic data, we looked at differences in comorbidities, tumor characteristics, staging, chemoradiation, operative procedure, operative variables, and pathological variables between BMI groups.
Statistical analyses performed included univariate analyses of demographic and complication data. For these analyses, we used χ2 or Fisher’s exact tests, as appropriate for categorical data and mean differences were examined for continuous data by ANOVA. Logistic regression was performed to estimate the magnitude of association (odds ratio) and 95% confidence interval of any complication. All multivariate analyses were controlled for type of surgery, age, preoperative stage, estimated blood loss, length of operation, administration of neoadjuvant chemoradiation, and diabetes. Survival analyses were performed by Kaplan– Meier curves with log rank tests for significance. All statistical tests performed were two-sided and declared at the 5% significance level. Statistical analyses were performed with Stata SE (Stata Statistical Software, release 9.0; StataCorp, College Station, TX).
RESULTS
Patient Demographics
From our esophageal database of 541 patients, 510 patients (94.2%) met our inclusion criteria for analysis. After excluding malnourished patients, there were 490 patients, 166 (33.9%) of whom were obese, 176 (35.9%) overweight, and 148 (30.2%) normal weight. Among the obese patients, most (102, 61.45%) had class I obesity (BMI 30–34); 47 patients (28.3%) had class II obesity (BMI 35–39), and only 17 (10.2%) had class III obesity (BMI ≥ 39). There were 420 men and 70 women with a mean age of 64 years (range, 28–86 years) at the time of surgery. Table 1 describes the demographics, comorbidities, and surgical and pathological characteristics of our patient population stratified by BMI.
TABLE 1.
Demographics, comorbidities, and surgical and pathologic variables stratified by BMI in 490 patients undergoing esophagectomy for cancer
| Characteristica | Normal weight (N = 148) n (%) |
Overweight (N = 176) n (%) |
Obese (N = 166) n (%) |
Pb |
|---|---|---|---|---|
| Clinical/pathological characteristics | ||||
| Male sex | 118 (79.7) | 159 (90.3) | 143 (86.1) | 0.02 |
| Age (years) (mean ± SD) | 65.3 ± 10.3 | 66.2 ± 9.7 | 62.4 ± 10.7 | 0.002 |
| Medical history | ||||
| Coronary artery disease or myocardial infarction | 29 (19.6) | 48 (27.3) | 44 (26.5) | 0.2 |
| Congestive heart failure | 4 (2.8) | 4 (2.4) | 7 (4.3) | 0.5 |
| Peripheral vascular disease | 11 (7.4) | 12 (6.8) | 7 (4.2) | 0.4 |
| Cerebrovascular disease | 13 (8.8) | 15 (8.5) | 11 (6.6) | 0.7 |
| Chronic obstructive pulmonary disease | 58 (39.2) | 68 (38.6) | 67 (40.4) | 0.9 |
| Diabetes | 15 (10.1) | 20 (11.4) | 39 (23.5) | 0.001 |
| Renal disease | 5 (3.4) | 5 (2.8) | 3 (1.8) | 0.6 |
| Liver disease | 1 (0.7) | 3 (1.7) | 1 (0.6) | 0.6 |
| Hiatal hernia | 30 (20.3) | 26 (14.8) | 47 (28.3) | 0.01 |
| Gastroesophageal reflux disease | 63 (42.6) | 84 (47.7) | 89 (53.6) | 0.2 |
| Barrett esophagus | 32 (21.6) | 43 (24.4) | 53 (31.9) | 0.1 |
| Alcohol history | 92 (62.2) | 93 (52.8) | 93 (56.0) | 0.2 |
| Smoking history | 120 (81.1) | 141 (80.1) | 134 (80.7) | 0.7 |
| ASA score | ||||
| 1 | 1 (0.8) | 2 (1.4) | 1 (0.7) | 0.3 |
| 2 | 63 (52.0) | 74 (52.1) | 66 (46.5) | |
| 3 | 57 (47.1) | 63 (44.3) | 75 (52.8) | |
| 4 | 0 | 3 (2.1) | 0 | |
| Preoperative serum albumin (mean ± SD) | 3.8 ± 0.5 | 3.9 ± 0.5 | 4.0 ± 0.5 | 0.3 |
| Adenocarcinoma | 118 (82.5) | 150 (90.9) | 139 (90.8) | 0.03 |
| Preoperative stage | ||||
| Tis | 2 (1.8) | 2 (1.5) | 7 (5.4) | 0.2 |
| T1 | 19 (17.1) | 30 (22.2) | 22 (17.0) | |
| T2 | 18 (16.2) | 23 (17.0) | 27 (20.9) | |
| T3 | 58 (52.2) | 66 (48.8) | 67 (51.9) | |
| T4 | 14 (12.6) | 14 (10.3) | 6 (0.5) | |
| N0 | 41 (36.9) | 50 (37.0) | 50 (38.7) | 0.7 |
| N1 | 69 (62.1) | 83 (61.4) | 79 (61.2) | |
| Nx | 1 (0.9) | 2 (1.5) | 0 | |
| AJCC 0–I | 16 (15.4) | 19 (15.2) | 23 (18.7) | 0.7 |
| AJCC II–IV | 88 (84.6) | 106 (84.8) | 100 (81.3) | |
| Postoperative stage | ||||
| AJCC 0–I | 13 (16.2) | 23 (14.2) | 25 (15.7) | 0.9 |
| AJCC II–IV | 67 (83.7) | 138 (85.7) | 134 (84.2) | |
| Treatment details | ||||
| Administration of CMT | 98 (66.2) | 96 (54.5) | 79 (47.6) | 0.004 |
| Type of surgery | ||||
| Transthoracic | 100 (72.5) | 127 (75.6) | 117 (73.13) | 0.3 |
| Transhiatal | 17 (12.3) | 19 (11.3) | 13 (8.1) | |
| Minimally invasive transthoracic | 6 (4.3) | 6 (3.6) | 3 (1.9) | |
| Minimally invasive transhiatal | 15 (10.9) | 16 (9.5) | 27 (16.8) | |
| Operation time (min) (mean ± SD) | 270 ± 86 | 266 ± 65 | 291 ± 78 | 0.01 |
| EBL (ml) | 292 ± 296 | 280 ± 264 | 356 ± 539 | 0.2 |
| No. of nodes collected in specimen | 8.5 ± 5.6 | 9.2 ± 5.2 | 8.5 ± 6.0 | 0.5 |
| Status of resection margins | ||||
| R0 (no residual disease) | 136 (93.8) | 161 (93.0) | 152 (93.8) | 0.9 |
| R1 (residual microscopic disease) | 6 (4.1) | 6 (3.5) | 6 (3.7) | |
| R2 (residual gross disease) | 3 (2.0) | 6 (3.5) | 4 (2.5) | |
| Administration of postoperative chemotherapy | 18 (18.5) | 45 (21.9) | 34 (18.7) | 0.7 |
Normal weight, BMI 20–24; overweight, BMI 25–29; obese, BMI ≥ 30
BMI body mass index, ASA American Society of Anesthesiology, CMT combined multimodal treatment, AJCC American Joint Committee on Cancer, EBL estimated blood loss
Data on all 490 patients were not available. Data were available on 405 patients for ASA score, 352 for albumin levels, 461 for histologic type, 352 for preoperative stage, 400 for postoperative stage, 489 for administration of CMT, 466 for type of surgery, 480 for status of resection margins, 397 for EBL, and 483 for postoperative chemotherapy
P values comparing differences across groups
Bold values indicate statistical significance
Obese patients tended to be younger (62.5 vs. 66.2 vs. 65.3 years, P = 0.002), male (86.1 vs. 90.3 vs. 79.7%, P = 0.02), and diabetic (23.5 vs. 11.4 vs. 10.1%, P = 0.001); they also had higher incidences of hiatal hernias (28.3 vs. 14.8 vs. 20.3%, P = 0.01). There were no statistical differences between groups in frequency of coronary artery disease (P = 0.22), peripheral vascular disease (P = 0.41), cerebrovascular disease (P = 0.74), congestive heart disease (P = 0.57), chronic obstructive pulmonary disease (P = 0.95), renal insufficiency (P = 0.69), American Society of Anesthesiologists score (P = 0.37), and history of smoking (P = 0.74) or alcohol use (P = 0.24). Gastroesophageal reflux (53.6 vs. 47.7 vs. 42.6%) and Barrett esophagus (31.9 vs. 24.4 vs. 21.6) were slightly more frequent in obese patients without reaching significance (P = 0.16 and P = 0.12, respectively). Serum albumin levels were similar across BMI group (4.0 vs. 3.9 vs. 3.8, P = 0.3).
Pathologic Features and Treatment Details
Eighty-eight percent of patients were diagnosed with adenocarcinoma and 12% with squamous-cell carcinoma. Incidence of adenocarcinoma was higher in overweight and obese patients (90.8 vs. 90.9 vs. 82.5%, P = 0.04). There was no significant difference in the distribution of preoperative American Joint Committee on Cancer stage among normal-weight, overweight, and obese patients (P = 0.7). However, a significantly smaller percentage of obese patients received neoadjuvant chemotherapy (47.6 vs. 54.5 vs. 66.2%, P = 0.004) compared to overweight and normal-weight patients. Type of esophagectomy performed (transthoracic vs. transhiatal, open vs. minimally invasive) did not differ among BMI groups. When examining the impact of BMI on collection of nodes for analysis, we found the mean number of lymph nodes included in the specimens did not differ by patient BMI (8.5 vs. 9.2 vs. 8.5, P = 0.5). Additionally, there were no significant differences across groups in rates of R0 resection (P = 0.9). Finally, no difference was noted in postoperative pathologic stage (P = 0.9) and rates of administration of postoperative chemotherapy (P = 0.7).
Perioperative Outcomes
The mean estimated blood loss in milliliters (356 vs. 281 vs. 293) for obese, overweight, and normal-weight patients did not differ among groups (0.2, respectively), nor did the mean length of hospitalization in the obese patient population (13.4 days compared to 12.1 days in overweight and 12.8 days in normal-weight patients; P = 0.3). However, the mean length of operation for obese patients was higher at 291 min, compared to 266 min in overweight and 271 min for normal-weight patients (P = 0.02). As shown in Table 2, there were no significant differences in the frequency of individual postoperative complications: respiratory failure (P = 0.7), pneumonia (P = 0.8), intraoperative cardiac complications (P = 1.0), extended intensive care unit stay (P = 0.9), anastomotic leak or stricture (respectively, P = 0.4 and P = 0.9), venous thrombosis (P = 0.8), pulmonary embolus (P = 0.3), surgical site infections (P = 0.8), or reoperations (P = 0.6). These results were maintained when examining the frequency of any complications across BMI groups (P = 0.3). The 30-day mortality among all patients was 2.65%. Stratification by BMI revealed no differences among groups: 3.61% in obese patients, 1.70% in overweight patients, and 2.70% in normal-weight patients (P = 0.56).
TABLE 2.
Univariate analysis of early and delayed postoperative complications and mortality stratified by BMI status
| Surgical complication | Normal weight (N = 148) n (%) |
Overweight (N = 176) n (%) |
Obese (N = 166) n (%) |
P |
|---|---|---|---|---|
| Intraoperative injury | 2 (1.4) | 1 (0.6) | 2 (1.2) | 0.7 |
| Intraoperative cardiac event | 0 | 1 (0.9) | 0 | 1.0 |
| Reoperation | 4 (2.7) | 7 (4.0) | 3 (1.8) | 0.6 |
| Prolonged ICU stay | 16 (10.8) | 19 (10.8) | 20 (12.0) | 0.9 |
| Surgical site infection | 8 (5.4) | 12 (6.8) | 12 (7.3) | 0.8 |
| Pneumonia | 24 (16.2) | 26 (14.8) | 29 (17.5) | 0.8 |
| Respiratory failure | 11 (7.4) | 10 (5.7) | 13 (7.8) | 0.7 |
| Anastomotic leak | 11 (7.4) | 7 (4.0) | 9 (5.4) | 0.4 |
| Anastomotic stricture | 21 (14.2) | 23 (13.1) | 25 (15.1) | 0.9 |
| Deep venous thrombosis | 3 (2.0) | 2 (1.1) | 3 (1.8) | 0.8 |
| Pulmonary embolus | 1 (0.7) | 4 (2.3) | 5 (3.0) | 0.3 |
| Any complicationsa | 59 (39.9) | 68 (38.6) | 77 (46.4) | 0.3 |
| Mortality | 4 (2.7) | 3 (1.7) | 6 (3.6) | 0.5 |
Normal weight, BMI 20–24; overweight, BMI 25–29; obese, BMI ≥ 30
BMI body mass index, ICU intensive care unit
Defined as the presence of one or more of the complications listed above in a single patient
Multivariate logistic regression analyses of three frequently occurring complications (surgical site infection, pneumonia, and anastomotic leak) and onset of any postoperative complication are presented in Table 3. In the multivariate analyses, there were no statistically significant associations between BMI ≥ 30 and postoperative complications controlling for age, diabetes, stage, neoadjuvant therapy, extent of surgery, intraoperative blood loss, and length of operation. Obese patients were found to be 1.32 times more likely to have any postoperative complication compared to normal-weight patients; however, this was not statistically significant (P = 0.1).
TABLE 3.
Multivariate analyses testing the association between BMI ≥ 30 and complications
| Characteristic | n | Crude OR | Adjusted OR for BMI ≥ 30 |
95% CI | P |
|---|---|---|---|---|---|
| Any complication | 77 | 1.32 | 1.31 | 0.9–1.9 | 0.1 |
| Anastomotic leak | 9 | 0.89 | 0.98 | 0.4–2.0 | 0.8 |
| Surgical site infection | 12 | 1.15 | 0.71 | 0.5–2.4 | 0.7 |
| Pneumonia | 29 | 1.11 | 0.66 | 0.7–1.8 | 0.6 |
Analyses were controlled for age, neoadjuvant therapy, stage, type of surgery, diabetes, length of operation, and estimated blood loss
BMI body mass index, OR odds ratio, 95% CI 95% confidence interval
We then sought to identify the possibility of a confounding volume and temporal relationship between obese patients and operative outcomes. Patients were stratified according to timing of their operation, as follows: time strata (TS) 1, 1994–1998; TS 2, 1999–2003; and TS 3, 2003–present. There were equal amounts of obese patients identified in each time strata: 34.9, 36.5, and 31.6%, respectively. When investigating the probability of any complication between increasing BMI across each time strata, there were again no differences in complications noted between obese patients, overweight, and normal-weight patients in TS 1 (P = 0.80), TS 2 (P = 0.13), and TS 3 (P = 0.20). We then compared all time strata to identify any potential differences in complications and BMI between strata (TS 1 vs. TS 2 vs. TS 3). No statistical differences were noted across time strata (P = 0.13), suggesting that our results of BMI and outcome were not confounded by more esophagectomies performed in obese patients later in our experience.
Long-Term Survival
Two patients (0.4%) were lost to follow-up. The median follow-up for the remaining 488 patients was 25 months (>47 months in 75% of patients). As shown in Fig. 1, there was a statistical improvement in 5-year OS and DFS noted in obese patients (respectively, 48, 41, 34%, P = 0.05; and 48, 44, 34%, P = 0.01; Fig. 1). The median OS was 58 months for obese, 43 months for overweight, and 24 months for normal-weight patients (P < 0.01). The median DFS was 58 months for obese, 38 months for overweight, and 21 months for normal-weight patients (P < 0.01).
FIG. 1.
Overall (a) and disease-free survival (b) by BMI
DISCUSSION
In the United States, approximately two-thirds of all adults are overweight or obese, and nearly half the U.S. population (45%) is expected to be obese by 2020.7,8 In line with recent epidemiologic data, most of our patients (342, 70%) were overweight or obese. It is readily evident that research on association of obesity with surgical risks and postoperative survival is increasingly important. However, despite the current national obesity trends, the surgical community has only recently started investigating effects of high BMI on surgical and oncologic outcomes. Data regarding the effects of obesity on perioperative outcomes of various surgical procedures have so far provided inconsistent results. Some authors have found that an elevated BMI is an independent predictor of morbidity, whereas others have argued that rates of complications in obese patients are directly attributable to clustered risk factors such as smoking or diabetes, and that high BMI is not a risk factor for major postoperative complications (perhaps aside from an increased incidence of minor wound complications) or death.9–21 Some of these discrepancies could be explained by use of different definitions of perioperative complications and obesity (especially in reports from eastern Asia), inclusion of heterogeneous surgical procedure, and lack of statistical power (especially for groups in the highest BMI categories).
In the present study, we found that an elevated BMI does not increase rates of perioperative complications, and may in fact be associated with improved long-term outcomes.
In the past, only a few studies have focused on BMI and gastroesophageal surgery. Several studies have found increased incidence of postoperative complications after gastrectomy in overweight or obese patients but no differences in mortality rates.22–24 Scipione et al. compared 133 profoundly obese patients (BMI ≥ 35) undergoing transhiatal esophagectomy for either benign or malignant diseases with a matched randomly selected, nonobese (BMI 18.5 to 30) control population of 133 patients.25 In this study, profoundly obese patients had higher intraoperative blood loss (361 vs. 492 ml, P = 0.001), greater need for partial sternotomy to gain access to the cervical esophagus (3 vs. 18, P = 0.001), and higher frequency of recurrent laryngeal nerve injury (0 vs. 6, P = 0.04). There were no statistically significant differences in the occurrence of chylothorax, wound infection, dehiscence rate, or length of hospital stay.
Thus far, only two papers have investigated influence of BMI on postoperative outcomes in patients operated on for esophageal cancer.26,27 In a series of 150 patients, Healy et al. found that obese patients have increased respiratory complications (P = 0.037), anastomotic leaks (P = 0.009), blood transfusions (P = 0.021), and length of stay (P = 0.001), but no difference in mortality.26 Morgan et al.27 found no correlation between BMI, morbidity, and mortality in 215 patients undergoing esophagectomy for cancer.
In our experience, even though patients with BMI > 25 were older and had a higher frequency of diabetes, we found that obesity did not increase the perioperative morbidity or mortality of esophageal resection for cancer. As in other previous reports, however, our analysis has a few limitations that need to be acknowledged. First, in our BMI calculation, we used weight before surgery, which did not take into account malnutrition and weight loss in patients who received neoadjuvant treatment. Confounding factors could have been introduced by patients with an elevated BMI before neoadjuvant treatment who lost enough weight to be classified in a lower-weight category at the time of surgery. Second, few patients (17, 10.2% of obese population) in our study had BMI > 40. As mentioned earlier, previous research has suggested that number of complications greatly increase in patients with extreme obesity.16 Because very few of these patients were included, our results should not be generalized to patients in the extreme obesity class. Third, this study is based on the experiences of high-volume esophageal surgeons, and the overall rates of intraoperative and postoperation complications are relatively low. Therefore, the number of events in patients who were obese and patients of normal weight might have been too small to adequately assess the differences between the two groups.
Aside from postoperative complications, our study also adds further data to existing evidence on influence of BMI on cancer treatment delivery and oncologic outcomes.
Although no difference in administration of neoadjuvant treatment was found by Morgan et al., Healy et al. demonstrated that obese patients were more likely to receive multimodal therapy (50 vs. 67%, P = 0.18), a finding exactly opposite to ours (Table 1).26,27 We do not have a clear explanation for these differences across studies; given the retrospective nature of these reports, it is possible that selection bias may have played a role.
Authors have investigated the adequacy of lymphadenectomy in obese patients during gastroesophageal surgery. Healy et al. demonstrated a marked decrease in number of collected lymph nodes in obese patients, a finding in line with a similar report showing impaired lymphadenectomy in obese patients with gastric cancer.26 Our findings parallel those of Morgan et al., who reported no statistically significant difference in number of lymph nodes between obese and nonobese patients.27 However, the number of collected lymph nodes in our experience was lower than what most authors would consider optimal, even after neoadjuvant treatment. We do not perform extended en-bloc resections; however, we do include in the specimen any connective, adipose, and lymphatic tissue surrounding the esophagus, stomach, and left gastric artery. It is conceivable that by increasing the number of collected nodes, a difference between groups could become evident.
Our finding of equal rate of R0 resections seem to support the concept that adequacy of oncologic esophageal resection is not compromised in obese patients, as previously reported by Healy et al.26
End points for our study were OS and DFS after esophagectomy.
At a median follow-up of 25 months, we found that an elevated BMI is statistically significantly associated with improved OS and DFS. We should acknowledge that this result might be influenced by unmeasured confounding factors, such as selection criteria and migration to lower BMI category of individuals with severe preoperative weight loss and malnutrition. However, our observation is not novel because a survival advantage in patients with high BMI has been repeatedly described for renal cancer and sporadically reported for esophagogastric cancers.28–30 Tokunaga et al. found that in their series of 7925 patients operated on for gastric cancer, BMI ≥ 25 was associated with improved OS (81.5 vs. 71.3%, P = 0.001) and disease- specific survival (84.0 vs. 76.7%, P = 0.001).31 Trivers et al. illustrated a population-based study including 1142 patients with esophageal or gastric cancer; among patients with esophageal adenocarcinoma (N = 293), overweight patients (BMI 25–29.9) had improved survival compared to normal weight (adjusted hazard ratio, 0.65; 95% confidence interval, 0.51–0.86). However, this study population was quite different from ours; it also included patients with unresectable disease and patients who did not undergo surgical treatment.29
In the articles by Healy et al. and Morgan et al. (median follow-up, respectively, 39 and 23 months), no difference in survival was seen between obese and nonobese patients after esophagectomy.26,27 Our data suggest a possible difference in biologic behavior of esophageal cancer in obese patients, which may portend a survival benefit. It is possible that multiple hormonal/endocrine and maybe nutritional factors contribute to the positive effects of obesity in esophageal cancer. Further basic biologic research is needed to elucidate this mystery.
In conclusion, our data confirm that carefully selected patients with high BMI can safely undergo esophageal resection without compromising rates of R0 resections and number of collected lymph nodes. Postsurgical morbidity and mortality are not affected by high BMI despite a higher rate of underlying diabetes. Obese patients were found to have longer DFS and OS in lieu of a lower incidence of preoperative multimodal treatment. The reasons behind these findings remain unclear and may be the result of selection bias and other confounding factors. Further studies are needed to clarify the biologic behavior of esophageal cancer in obese patients.
Footnotes
CONFLICT OF INTEREST The authors declare no conflict of interest.
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