Copyright ©2013 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Jul 28, 2013; 19(28): 4596-4606
Published online Jul 28, 2013. doi: 10.3748/wjg.v19.i28.4596
Impact of being overweight on the surgical outcomes of patients with gastric cancer: A meta-analysis
Xiang-Song Wu, Wen-Guang Wu, Mao-Lan Li, Jia-Hua Yang, Qi-Chen Ding, Lin Zhang, Jia-Sheng Mu, Jun Gu, Ping Dong, Jian-Hua Lu, Ying-Bin Liu
Xiang-Song Wu, Wen-Guang Wu, Mao-Lan Li, Jia-Hua Yang, Qi-Chen Ding, Lin Zhang, Jia-Sheng Mu, Jun Gu, Ping Dong, Jian-Hua Lu, Ying-Bin Liu, Department of General Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China
Author contributions: Wu XS, Wu WG and Liu YB designed research; Li ML, Yang JH, Ding QC and Zhang L performed research; Mu JS, Gu J, Dong P and Lu JH contributed new reagents or analytic tools; Wu XS, Wu WG, Lu JH and Liu YB analyzed data; Wu XS, Wu WG and Liu YB wrote the paper; Wu XS and Wu WG contributed equally to this work.
Correspondence to: Ying-Bin Liu, MD, PhD, Department of General Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, 1665 Kongjiang Rd, Shanghai 200092, China.
Telephone: +86-21-25077880 Fax: +86-21-25077880
Received: April 15, 2013
Revised: May 31, 2013
Accepted: June 19, 2013
Published online: July 28, 2013


AIM: To investigate the effect of being overweight on the surgical results of patients with gastric cancer.

METHODS: Comprehensive electronic searches of the PubMed, Web of Science, and Cochrane Library databases were conducted. Studies were identified that included patients with surgical complications from gastric cancer who were classified as normal weight [body mass index (BMI) < 25 kg/m2] or overweight (BMI ≥ 25 kg/m2). The operative time, retrieved lymph nodes, blood loss, and long-term survival were analyzed. A subgroup analysis was conducted based on whether patients received laparoscopic or open gastrectomy procedures. All statistical tests were performed using ReviewerManager 5.1.2 software.

RESULTS: This meta-analysis included 23 studies with 20678 patients (15781 with BMI < 25 kg/m2; 4897 with BMI ≥ 25 kg/m2). Overweight patients had significantly increased operation times [MD: -29.14; 95%CI: -38.14-(-20.21); P < 0.00001], blood loss [MD: -194.58; 95%CI: -314.21-(-74.95); P = 0.001], complications (RR: 0.75; 95%CI: 0.66-0.85; P < 0.00001), anastomosis leakages (RR: 0.59; 95%CI: 0.42-0.82; P = 0.002), and pancreatic fistulas (RR: 0.486; 95%CI: 0.34-0.63; P < 0.00001), whereas lymph node retrieval was decreased significantly in the overweight group (MD: 1.69; 95%CI: 0.75-2.62; P < 0.0001). In addition, overweight patients had poorer long-term survival (RR: 1.14; 95%CI: 1.07-1.20; P < 0.0001). No significant difference was detected for the mortality and length of hospital stay.

CONCLUSION: This meta-analysis demonstrates that a high BMI not only increases the surgical difficulty and complications but also impairs the long-term survival of patients with gastric cancer.

Key Words: Overweight, Body mass index, Gastric cancer, Gastrectomy

Core tip: Surgical and postoperative complications are believed to be greater for overweight patients with gastric cancer, but this is controversial due to conflicting results from previous studies. This meta-analysis identified 23 studies with a total of 20678 patients, and the results indicate that overweight patients had significantly increased operation times, blood loss, complications, anastomosis leakages, and pancreatic fistulas, whereas lymph node retrieval was decreased significantly in the overweight group. In addition, overweight patients had poorer long-term survival. Therefore, being overweight not only increased the surgical difficulty and complications but also impaired the long-term survival of patients with gastric cancer.

Citation: Wu XS, Wu WG, Li ML, Yang JH, Ding QC, Zhang L, Mu JS, Gu J, Dong P, Lu JH, Liu YB. Impact of being overweight on the surgical outcomes of patients with gastric cancer: A meta-analysis. World J Gastroenterol 2013; 19(28): 4596-4606

The increasing global prevalence of overweight and obese individuals is problematic[1,2] for Western countries[3] and is also a concern for Eastern countries such as China[4] and South Korea[5]. Consequently, abdominal surgeries are increasingly more difficult because increasing numbers of surgeries are performed on overweight and obese individuals. In particular, gastric cancer studies[6,7] reported that excess body weight is associated with unfavorable surgical results, including longer operating times, decreased lymph node retrieval, increased postoperative complications, and decreased survival rates. Radical gastrectomy with D2 node dissection is the recommended surgical approach for patients with resectable (curable) gastric cancer[8]. However, the results of postoperative morbidity, mortality, and long-term survival after D2 node dissection differed significantly between different studies from Asia and Europe[8-14]. This discrepancy may be due to the variable prevalence of overweight patients in Western and Eastern countries. Excess visceral fat in overweight patients theoretically complicates manipulation of the omentum and impedes lymph node dissection during radical gastrectomy due to decreased visualization of the branches of the arteria celiaca, which could increase surgical and postoperative complications and mortality. However, a number of studies[15-18] reported conflicting results about the effect of being overweight on both the short-term and long-term surgical outcomes for patients with gastric cancer. To more comprehensively understand this issue, we conducted a meta-analysis.

Search strategy

Two authors (Wu XS and Wu WG) independently conducted comprehensive electronic searches of the PubMed, Web of Science, and Cochrane Library databases for all dates prior to January 2013. The search strategy was unrestricted for English-language journals and used combinations of MeSH and text words for overweight, body mass index (BMI), gastric cancer, and gastrectomy, e.g., the string “Body Mass Index” (Mesh) or “overweight” (MeSH Terms) or overweight (Text Word) and “gastrectomy” (MeSH Terms) or gastrectomy (Text Word) or “stomach neoplasms” (MeSH Terms) or gastric cancer (Text Word). In addition, reference lists of all retrieved articles were manually searched for additional studies that were missed by the electronic search.

Inclusion and exclusion criteria

The inclusion criteria for the meta-analysis were studies that examined the influence of body weight on gastric cancer surgical outcomes (morbidity, anastomotic leakage, pancreatic fistula, postoperative mortality, operative time, lymph node retrieval, blood loss, postoperative hospital stay, and long-term survival). In the studies we chose, there were patients with normal-weight and overweight presurgical BMIs based on World Health Organization definitions (overweight BMI ≥ 25 kg/m2; healthy-weight BMI < 25 kg/m2)[19,20]. Reviews, case reports, and series reports were excluded. When data were presented in more than one publication, publications with smaller data sets were excluded. Disagreements regarding a study’s eligibility were resolved based on a consensus of reviews from two additional authors (Li ML and Yang JH).

Outcome measures analyzed

Three outcome variables, including the operation time, number of retrieved lymph nodes, and blood loss, were analyzed as indices of the surgical difficulty. We estimated the influence of a high BMI on surgical safety, morbidity, anastomotic leakage, pancreatic fistula, postoperative mortality, and postoperative hospital stay. The long-term survival of overweight and healthy-weight patients was also compared as an index of successful clinical resolution.

Data extraction and risk of bias assessment

Data were extracted from each study by two independent reviewers (Ding QC and Zhang L), who also rated the overall quality of each outcome according to the recommendation of the Cochrane Handbook for Systematic Reviews of Interventions[21]. The criteria to assess nonrandomized studies were taken from the Grading of Recommendations Assessment, Development, and Evaluation Working Group[22]. By combining the aforementioned recommendations, the following aspects of each included study were evaluated: the application of an internal control, adequate control of confounding factors, adequate reporting of outcomes, and the absence of a variable definition. Agreement for ratings was achieved via author consensus, as needed.

Statistical analysis

The statistical analysis was performed using ReviewerManager (Version 5.1.2, 2011, The Nordic Cochrane Centre, Cochrane Collaboration, ). Statistical methods were based on the Cochrane Handbook for Systematic Reviews of Interventions[21]. Heterogeneity was checked using χ2 tests, and P < 0.1 was the cutoff for statistical significance. A random effects model was applied for the meta-analysis using a more conservative perspective. Data from different trials reporting the same or similar outcomes were combined. The results were expressed using the RR for binary variables and the MD for continuous variables. Methods for relevant data extraction were based on Tierney et al[23]. The cutoff for statistical significance was P < 0.05, and the 95%CI was presented for each effect measure. Subgroup analysis was conducted based on whether patients received a laparoscopic gastrectomy or a total gastrectomy. Whenever possible, all analyses were based on the intention-to-treat principle. Publication bias exploration using a funnel plot and Egger’s regression method[24] was performed if at least 10 trials were included in an outcome variable. Publication bias was considered to exist for P < 0.05.

Description of the included trials

We retrieved 996 records from the PubMed search and 45 records from the manual search. Twenty-three trials[15-18,25-43], which included multiple study types, procedures, percentages of patients with early gastric cancer, therapeutic modalities, and BMI cutoffs, met the eligibility criteria and were included in the meta-analysis (Table 1). Excluded reports largely had irrelevant topics. Twelve studies were excluded because they did not define overweight patients using the 25 kg/m2 criteria. Figure 1 shows the flow chart for the selection of articles based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses[44]. This meta-analysis identified patients with healthy-weights (BMI < 25 kg/m2) (n = 15781) and patients who were overweight (BMI ≥ 25 kg/m2) (n = 4897). For five included studies[27,28,30,33,35] that classified patients using more than one BMI cutoff point, binary variables were successfully combined, but it was not possible to pool these studies’ continuous variables. Only four studies[16,17,32,35] were considered to have a low risk of bias, and all others were considered to have high risk of bias. Most of them were considered high risk because of the selective reporting or absence of variables definition.

Table 1 Basic data of included studies.
StudyCountryInclusion periodSample sizeStudy typeFollow up periodPercentage of T1 (normal weight vs overweight)Percentage of N0 (normal weight vs overweight)Percentage of stage 1/2 (normal weight vs overweight)Percentage of differentiated (normal weight vs overweight)Type of gastrectomyNode dissectionLaparoscopicChemotherapy/radiotherapyBMI cutoff pointRisk of internal controlRisk of confounding factorsRisk of slective reportRisk of variables definition
Gretschel et al[27]Germany1992-2001199Retrospective-15.8% vs 31.6%26.8% vs 45.3%Not statedNot statedTotalD2Not statedNot stated25, 30LowHighHighHigh
Yamada et al[17]Japan1999-2005248Retrospective8-118 mo53.2% vs 78.3%Not stated89.9% vs 93.3%Not statedDistalD2141 LADGNot stated25LowLowLowLow
Oh et al[29]South Korea2009-200961Prospective-Not statedNot statedNot statedNot statedTotalD2Not statedNot stated25LowHighLowLow
Nobuoka et al[40]Japan1992-2008644Retrospective-Not statedNot stated53.8% vs 56.6%Not statedTotalD2Not statedChemotherapy for advanced cancer and recurrence25LowHighLowLow
Tsujinaka et al[32]Japan1995-2001523Prospective-0.0% vs 0.0%Not statedNot statedNot statedNot statedD2; D3NoNot stated25LowLowLowLow
Ohno et al[37]Japan2004-2009197Retrospective-73.9% vs 77.5%Not stated87.2% vs 95.0%57.3% vs 57.5%LADG; ODGD1a; D1b; D2120 LADGNot stated25LowLowLowHigh
Pacelli et al[33]Italy2000-2006145Retrospective-Not statedNot statedNot statedNot statedDistal; totalD2 + D3NoNo preoperative chemotherapy18.5, 25, 30LowHighLowLow
Yoshikawa et al[39]Japan2007-200966Retrospective-Not statedNot stated92.4% vs 100.0%Not statedLADG; LATGcD1ab + D256 LADG; 10 LATGNot stated25LowLowLowHigh
Murphy et al[35]United Kingdom1997-200250Prospective-Not statedNot stated29.6% vs 65.2%Not statedNot statedD2NoNo preoperative chemotherapy20, 25, 30LowLowLowLow
Yasuda et al[34]Japan1994-200299Retrospective48 mo100.0% vs 100.0%93.8% vs 95.2%Not stated80.7% vs 87.5%LADGD1LADGNot stated25LowLowLowHigh
Lee et al[38]South Korea-20051485RetrospectiveAt least 3 moNot statedNot stated89.1% vs 89.0%Not statedLADGD1a; D1bLADGNot stated25LowHighLowHigh
Kulig et al[18]Poland1986-19981992Retrospective104 mo13.8% vs 10.6%17.5% vs 15.0%Not statedNot statedDistal; proximal; totalD1; D2; D2+NoNot stated25LowHighLowHigh
Kim et al[30]South Korea2005-20101100Prospective-Not statedNot statedNot statedNot statedLADGD2LADGNot stated25, 30LowHighLowHigh
Inagawa et al[28]Japan1990-1997293Retrospective10-104 moNot statedNot stated88.7% vs 94.0%Not statedDistalD2-Not stated20, 25LowLowLowHigh
Kawamura et al[36]Japan2003-2008473Retrospective-Not statedNot stated100.0% vs 100.0%Not statedDistalRegional249 LADGNot stated25LowLowLowHigh
Ojima et al[31]Japan1992-2002689RetrospectiveAt least 60 mo55.3% vs 51.7%66.1% vs 65.5%Not stated53.4% vs 56.9%Distal; proximal; totalD1; D2; D2+-No preoperative chemotherapy25LowHighLowLow
Tokunaga et al[15]Japan1970-20047925RetrospectiveAt least 60 mo51.0% vs 60.0%61.0% vs 68.0%75.0% vs 83.0%45.0% vs 40.0%Distal; proximal; totalNot stated-Not stated25LowHighHighLow
Oh et al[16]South Korea2000-2003410Retrospective50 mo15.7% vs 20.9%41.8% vs 40.4%47.6% vs 46.5%32.5% vs 35.4%TotalD2-Not stated25LowLowLowLow
Tanaka et al[26]Japan2001-2007191Retrospective-Not statedNot statedNot statedNot statedTotalD1; D2-Not stated25LowHighLowHigh
Kunisaki et al[25]Japan2002-2008152Retrospective-Not statedNot statedNot statedNot statedLADGD1a; D1b; D2LADGNot stated25LowHighHighHigh
Lee et al[42]South Korea2006-2010243Retrospective-Not statedNot stated100.0% vs 100.0%Not statedDistalNot statedNot statedNot stated25LowLowHighHigh
Bickenbach et al[43]United States1985-20071853Retrospective35 mo24.6% vs 29.8%44.5% vs 48.3%58.6% vs 65.9%Not statedNot statedD1; D2; D2+Not statedNot stated25LowHighLowLow
Deguchi et al[41]Japan1999-20081640Retrospective-Not statedNot statedNot statedNot statedProximal; totalD0; D1; D2; D2+Not statedNot stated25LowHighLowLow
Figure 1
Figure 1 PRISMA flow chart showing study selection process. BMI: Body mass index.
Surgical results for all patients

Overweight patients had significantly longer operation times [MD: -29.14; 95%CI: -38.14-(-20.21); P < 0.00001, Figure 2A], greater blood loss [MD: -194.58; 95%CI: -314.21-(-74.95); P = 0.001], reduced lymph node retrieval (MD: 1.69; 95%CI: 0.75-2.62; P < 0.0001) (Table 2), and more postoperative complications (RR: 0.75; 95%CI: 0.66-0.85; P < 0.00001, Figure 2B). Specifically, anastomotic leakage (RR: 0.59; 95%CI: 0.42-0.82; P = 0.002, Figure 2C) and pancreatic fistula (RR: 0.486; 95%CI: 0.34-0.63; P < 0.00001, Figure 2D) were significantly greater in the overweight cohort. There was no significant difference between the two cohorts for the postoperative mortality or postoperative hospital stay. Patients in the normal-weight cohort had higher cancer-specific survivorship (RR: 1.14; 95%CI: 1.07-1.20; P < 0.0001, Figure 2E).

Table 2 Summary statistics of pooled data comparing normal body mass index vs high body mass index for overall patients, patients receiving open gastrectomy and laparoscopic gastrectomy.
Outcome variablesStudiesPooled patientsPooled RR or MD or HR95%CITest for overall effect
Test for heterogeneity
ZP valueI2P value
Overall patients
Operative time95905-29.14-38.08, -20.216.39< 0.0000170%  0.0008
Retrieved lymph nodes64612  1.69  0.75, 2.623.55  0.00049%  0.36
Blood loss52096-194.58-314.21, -74.953.19  0.00186%< 0.00001
Morbidity1717514  0.75  0.66, 0.854.48< 0.0000158%  0.001
Anastomotic leak1912367  0.59  0.42, 0.823.07  0.00234%  0.07
Pancreatic fistula82959  0.46  0.34, 0.634.90< 0.0000116%  0.3
Mortality1316590  0.86  0.58, 1.290.71  0.480%  0.76
Postoperative hospital stay64552-5.83-13.44, 1.781.5  0.1998%< 0.00001
Cancer-specific survival512321  1.14  1.07, 1.204.21< 0.000185%< 0.0001
Patients receiving open gastrectomy
Operative time72179-25.24-33.53, -16.955.97< 0.0000153%  0.05
Retrieved lymph nodes62838  3.81-0.34, 7.961.8  0.0791%< 0.00001
Blood loss51708-212.93-301.04, -124.824.74< 0.0000174%  0.004
Morbidity1112510  0.78  0.66, 0.942.68  0.00764%  0.002
Anastomotic leak147320  0.58  0.38, 0.892.51  0.0137%  0.08
Pancreatic fistula62470  0.46  0.38, 0.674.03< 0.000137%  0.16
Mortality1012763  1.17  0.69, 2.010.58  0.560%  0.83
Postoperative hospital stay41339-2.04-6.00, 1.911.01  0.3180%  0.002
Cancer-specific survival412180  1.14  1.07, 1.204.23< 0.000189%< 0.00001
Patients receiving laparoscopic gastrectomy
Operative time41845-15.06-17.41, -12.7012.52< 0.000010%  0.52
Retrieved lymph nodes31746  2.11  1.35, 2.885.39< 0.000010%  0.61
Blood loss3360-47.83-68.12,-27.534.62< 0.0000147%  0.15
Morbidity63151  0.48  0.29, 0.792.91  0.00467%  0.009
Anastomotic leak63194  0.83  0.42, 1.650.53  0.632%  0.2
Pancreatic fistula3489  0.3  0.08, 1.201.7  0.0910%  0.33
Mortality31833  0.4  0.12, 1.301.53  0.130%  0.41
Postoperative hospital stay31833  0.17-0.80, 1.150.35  0.7334%  0.22
Cancer-specific survival1141  1.65  0.13, 20.700.39  0.7Not applicableNot applicable
Figure 2
Figure 2 Forest plot. A: For operative time showing overweight in association with longer duration of operative time than non-overweight; B: For morbidity showing overweight in association with more postoperative complication than non-overweight; C: For anastomotic leak indicating that overweight correlates with higher rate of anastomotic leak; D: For pancreatic fistula showing overweight in association with more pancreatic fistula than non-overweight; E: For long-term survival favoring normal weight with better survival results. BMI: Body mass index.

There was significant heterogeneity in the operation time, morbidity, anastomotic leakage, blood loss, long-term survival, and postoperative hospital stay results. No heterogeneity was detected for any of the other assessed outcomes. No publication bias was detected for the morbidity outcomes (P = 0.05), anastomotic leakage (P = 0.291), or mortality (P = 0.272).

Surgical results for patients receiving open gastrectomy

Overweight patients who received open gastrectomy had longer operation times [MD: -25.24; 95%CI: -33.53-(-16.95); P < 0.00001], greater intraoperative blood loss [MD: -212.93; 95%CI: -301.04-(-124.82); P < 0.00001], increased postoperative complications (RR: 0.78; 95%CI: 0.66-0.94; P = 0.007), more anastomotic leakage (RR: 0.58; 95%CI: 0.38-0.89; P = 0.01), and increased pancreatic fistulas (RR: 0.46; 95%CI: 0.38-0.67; P < 0.0001) compared with patients with healthy weights (Table 2). There were no significant differences between the cohorts for mortality, postoperative hospital stay, or number of retrieved lymph nodes. Non-overweight patients had better overall survival results than overweight ones (RR: 1.14; 95%CI: 1.07-1.20; P < 0.0001).

There was significant heterogeneity in the morbidity, anastomotic leakage, operative time, number of retrieved lymph nodes, blood loss, and postoperative hospital stay. No heterogeneity was found in any of the other assessed outcomes. There was no evidence of publication bias (P > 0.05 for all 3 of the following outcomes: morbidity, anastomotic leakage, and mortality).

Surgical results for patients receiving laparoscopic gastrectomy

Overweight patients receiving laparoscopic gastrectomies had increased complications (RR: 0.48; 95%CI: 0.29-0.79; P = 0.004), longer operation times [MD: -15.06; 95%CI: -17.41-(-12.70); P < 0.00001], more blood loss [MD: -47.83; 95%CI: -68.12-(-27.53); P < 0.00001], and fewer retrieved lymph nodes (MD: 2.11; 95%CI: 1.35-2.88; P < 0.00001) than healthy-weight patients (Table 2). There were no significant differences in any of the other outcomes. Morbidity was a heterogeneous outcome with very low quality, whereas the other outcomes were rated as low quality. Egger’s regression method was not applied in this subgroup analysis because none of the outcome variables included at least 10 trials.

Surgical results for patients receiving total gastrectomy

Overweight patients receiving total gastrectomies had increased complications (RR: 0.68; 95%CI: 0.56-0.84; P = 0.0003), more pancreatic fistulas (RR: 0.56; 95%CI: 0.42-0.74; P < 0.0001), longer operation times [MD: -23.94; 95%CI: -32.62-(-15.25); P < 0.00001], more blood loss [MD: -293.84; 95%CI: -401.80-(-185.87); P < 0.00001], and fewer retrieved lymph nodes (MD: 3.99; 95%CI: 1.14-6.83; P = 0.006) than healthy-weight patients. There were no significant differences in any of the other outcomes.

Surgical results for patients receiving subtotal gastrectomy

Overweight patients receiving subtotal gastrectomies had increased complications (RR: 0.61; 95%CI: 0.40-0.94; P = 0.02), longer operation times [MD: -22.02; 95%CI: -29.18-(-14.86); P < 0.00001], and more blood loss [MD: -58.36; 95%CI: -93.56-(-23.45); P = 0.001] than healthy-weight patients. There were no significant differences in any of the other outcomes, including pancreatic fistulas and the number of retrieved lymph nodes.


Theoretically, comorbidity risk factors[45] and surgical complications could cause prolonged surgical times, increased blood loss, more postoperative complications, and greater intraoperative mortality. However, the effects of comorbidity risk factors are uncertain because published papers[25-43] assessing the relationship between being overweight and poor surgical outcomes have reported conflicting results, especially for the outcome variables, such as morbidity, mortality, and long-term survival.

We evaluated the operation time, intraoperative blood loss, and number of retrieved lymph nodes as indices of the surgical difficulty. Both the operation time and blood loss for overweight patients with gastric cancer were significantly higher than for the normal-weight cohort, regardless of whether open gastrectomy or laparoscopic gastrectomy was performed. Being overweight was also correlated with significantly fewer retrieved lymph nodes. Two reasons may contribute to the lower number of retrieved lymph nodes[6]. First, the excess fat tissue in the abdomen could limit the node dissection for overweight patients. Second, pathologists would have difficulty obtaining lymph nodes from a large amount of adipose tissue.

The relationship between high BMI and surgical safety for patients with gastric cancer is controversial. In the 17 trials providing data about morbidity, ten studies[18,29,33-36,38,39,42,43] did not indicate that being overweight affected the overall postoperative complication rate, whereas the remaining 7[15,16,25,28,30,32,40] did. Our meta-analysis strongly suggests that overweight patients have more complications. More specifically, the rates of pancreatic fistula and anastomotic leakage were significantly higher in the overweight patients, which also was true in the subgroup analysis of patients receiving open gastrectomy. According to these results, it is clear that overweight patients have high risks of postoperative complications. However, it is still uncertain whether a high BMI has a direct influence on the postoperative morbidity. High BMIs directly affect the operation times for cholecystectomies, colectomies, and unilateral mastectomies but have no direct relationship with complications[46]. Increased operation times and blood loss secondary to high BMI are also responsible for high postoperative complication rates[28,31], which is likely because prolonged operative times prolong the duration of anesthesia and increase the risk of thromboembolic, cardiac, and respiratory complications. Our study found strong evidence (RR < 0.5) for an association between being overweight and high rates of pancreatic fistula, as suggested in earlier reports[13,32]. This effect on the occurrence of a pancreatic fistula could be because removal of overweight patients’ pancreatic capsules is difficult; they have poor differentiation between the pancreas and excess pancreatic fat deposition[47,48]. This could also hamper peripancreatic node dissection and increase the potential for iatrogenic injury to pancreatic tissue. More interestingly, according to one included study[26], minimal damage to the pancreatic tissue, which would never cause a pancreatic fistula in patients with low visceral fat area (VFA), could result in pancreatic fistula in high-VFA patients. Visceral fat maybe play an important role in the pathogenesis from pancreatic injury to pancreatic fistula. Therefore, being overweight could have a direct influence on the postoperative complication rate, as is the case for pancreatic fistulas. Although overweight patients suffered more complications, no difference was detected for mortality, which might be attributed to the advancement of perioperative management. Changes in perioperative management have dramatically decreased the death rate from serious postoperative complications such as pancreatic fistula and anastomotic leakage. Thus, it is safe to perform radical gastrectomy in overweight patients.

Relevant studies reported conflicting results on the relationship between being overweight and long-term survival[6,7,28,31,40,49,50]. Theoretically, excess visceral fat and being overweight could negatively affect survivorship by increasing the rates of coexisting disease and postoperative complications. In addition, according to Adachi et al[6], incomplete lymph node dissection in overweight patients could result in retention of metastatic nodes that are responsible for the worse survivorship. Increased long-term survival in normal-weight patients was found in the current review and is consistent with the hypothesis that excess accumulation of visceral fat could impair patient survival and promote tumor recurrence. Unfortunately, among the 23 analyzed studies, only five were included in the analysis of survivorship; thus, the survivorship results, with fewer data points, are less convincing. However, during the data extraction, we noticed that the percentage of patients with early gastric cancer was greater for the overweight cohort. Compared with advanced gastric cancer patients, patients with early gastric cancer have a significantly higher long-term survival rate[51]. Although the overweight cohort had more patients with early gastric cancer, who might have a more promising prognosis, the overall long-term survival was still significantly lower in this cohort. This is indirect evidence that being overweight can impair the long-term survival of gastric patients. In addition, we do not think that the decreased long-term survival was caused by the increasing comorbidity related to being overweight, such as diabetes and cardiovascular disease because we used cancer-specific survival as the indicator of long-term survival.

High BMIs increase the difficulty and decrease the safety of laparoscopic gastrectomy procedures, as is the case with open gastrectomy. These findings are consistent with some previous studies[25,30,36]. However, other studies[37-39] did not show significant differences in the morbidity between overweight and normal-weight cohorts for laparoscopic gastrectomy. Unlike open gastrectomy, laparoscopic gastrectomy can achieve excellent visibility even for overweight patients because the pneumoperitoneum creates sufficient extra space in the abdominal cavity. Although the laparoscopic procedure has these advantages, the results of our study still suggest that being overweight negatively affects the difficulty and safety of laparoscopic gastrectomy.

Moreover, being overweight increases the difficulty and impairs the safety of both total and subtotal gastrectomies. However, a subtotal gastrectomy seems to be safer than a total gastrectomy for overweight patients because subtotal gastrectomy did not increase the rate of pancreatic fistula occurrence in the overweight group, which is a severe complication after gastric surgery. In addition, after subtotal gastrectomy, the numbers of retrieved lymph nodes did not differ significantly between the two cohorts, while there was a difference in the number of lymph nodes retrieved after total gastrectomy.

Because of the relationship between being overweight and impaired surgical safety, surgeons should be more careful when performing radical gastrectomy in the future. In addition, for suitable cases, performing a subtotal gastrectomy might be safer than performing a total gastrectomy.

This meta-analysis has some limitations. First, most of the studies in this meta-analysis were rated as low or very low quality due to their retrospective study designs. All included studies are nonrandomized in nature and have a risk of bias. Although randomized trials are the gold standard for study design, random allocation of patients with different BMIs is hardly feasible. To overcome this limitation in the future, more rigorously designed studies with a good balance of other confounding factors, such as age and tumor-node-metastasis stage, are needed. Second, although BMI ≥ 25 kg/m2 was used as a criterion for classifying patients as overweight, it may be not the best index because the distribution of fat tissue could differ greatly between individuals, even those with the same BMI[26,52]. Therefore, individuals with the same BMI could have different surgical outcomes due to their different fat distributions. Some studies[26,39,53] have indicated that the VFA is a better index than BMI. Third, the procedure type and extent of node dissection differed among the studies in our meta-analysis. Moreover, gastric cancer was more prevalent in Eastern countries than Western ones. As a result, surgeons from Eastern countries could have more experience in performing the surgeries and dealing with the postoperative complications. Additionally, the higher incidence of gastric cancer has led to earlier diagnosis in Asian countries. Therefore, the proportions of early gastric cancer cases differed between studies from the East and West in this review. All these factors could account for the heterogeneity of some results and jeopardize the reliability of the conclusions. The limitations in the previously published data could potentially affect the analysis of both groups. Publication bias was a possible source of bias during the meta-analysis because positive results are more likely to be published. Several methods have been proposed for detecting bias and, in this review, we detected publication bias by a funnel plot and Egger’s regression method, which is reliable when the number of included trials is not less than 10. It turned out that our results did not show significant publication bias (P > 0.05) for the parameters in this review.

In conclusion, this meta-analysis indicates that overweight patients with gastric cancer have increased surgical complications and worse short-term operative outcomes than patients with healthy weights, and these results were consistent for patients who underwent either a laparoscopic gastrectomy or an open gastrectomy. Although no evidence was detected to indicate that being overweight had higher postoperative morbidity, being overweight decreased the long-term survival.


The increasing global prevalence of overweight and obese individuals is problematic for Western countries and is also a concern for Eastern countries such as China and South Korea. Surgical results and postoperative complications are believed to be greater for overweight patients with gastric cancer, but this is controversial due to conflicting results from previous studies.

Research frontiers

The postoperative morbidity, mortality, and long-term survival after D2 node dissection differed between different studies from Asia and Europe. It is possible that this discrepancy is due to the differing prevalence of overweight patients in Western and Eastern countries. However, different studies have conflicting results for the effect of being overweight on both the short-term and long-term surgical outcomes for gastric cancer patients.

Innovations and breakthroughs

To the knowledge, this is the first meta-analysis studying the effect of being overweight on the surgical results of gastric cancer patients. The authors found that overweight patients with gastric cancer have increased surgical complications and worse short-term operative outcomes than patients with healthy weights, and these results were consistent for patients who underwent either a laparoscopic gastrectomy or an open gastrectomy.


This meta-analysis emphasizes the influence of being overweight on gastric cancer surgical results. Surgeons should pay particular attention when they perform radical gastric cancer surgery.

Peer review

Overall, this manuscript provides a detailed and comprehensive review of the influence of elevated patient body mass index on outcomes following gastrectomy as a treatment for cancer. This article includes information about the complications of gastric surgery and has potential clinical implications. Finally, this meta-analysis demonstrates that being overweight is significantly correlated with surgical difficulty, a high rate of postoperative complications, and poor survival in patients with gastric cancer.


P- Reviewers Aoyagi K, Arigami T, Baba H, Cui G, Deans C, Goral V, Ji JF, Zhu BS S- Editor Gou SX L- Editor A E- Editor Li JY

1.  Kelly T, Yang W, Chen CS, Reynolds K, He J. Global burden of obesity in 2005 and projections to 2030. Int J Obes (Lond). 2008;32:1431-1437.  [PubMed]  [DOI]
2.  Abelson P, Kennedy D. The obesity epidemic. Science. 2004;304:1413.  [PubMed]  [DOI]
3.  Flegal KM, Carroll MD, Kit BK, Ogden CL. Prevalence of obesity and trends in the distribution of body mass index among US adults, 1999-2010. JAMA. 2012;307:491-497.  [PubMed]  [DOI]
4.  Shen J, Goyal A, Sperling L. The emerging epidemic of obesity, diabetes, and the metabolic syndrome in china. Cardiol Res Pract. 2012;2012:178675.  [PubMed]  [DOI]
5.  Oh SW. Obesity and metabolic syndrome in Korea. Diabetes Metab J. 2011;35:561-566.  [PubMed]  [DOI]
6.  Adachi W, Kobayashi M, Koike S, Rafique M, Nimura Y, Kuroda T, Iida F. The influence of excess body weight on the surgical treatment of patients with gastric cancer. Surg Today. 1995;25:939-945.  [PubMed]  [DOI]
7.  Lee JH, Paik YH, Lee JS, Ryu KW, Kim CG, Park SR, Kim YW, Kook MC, Nam BH, Bae JM. Abdominal shape of gastric cancer patients influences short-term surgical outcomes. Ann Surg Oncol. 2007;14:1288-1294.  [PubMed]  [DOI]
8.  Songun I, Putter H, Kranenbarg EM, Sasako M, van de Velde CJ. Surgical treatment of gastric cancer: 15-year follow-up results of the randomised nationwide Dutch D1D2 trial. Lancet Oncol. 2010;11:439-449.  [PubMed]  [DOI]
9.  Bonenkamp JJ, Songun I, Hermans J, Sasako M, Welvaart K, Plukker JT, van Elk P, Obertop H, Gouma DJ, Taat CW. Randomised comparison of morbidity after D1 and D2 dissection for gastric cancer in 996 Dutch patients. Lancet. 1995;345:745-748.  [PubMed]  [DOI]
10.  Cuschieri A, Weeden S, Fielding J, Bancewicz J, Craven J, Joypaul V, Sydes M, Fayers P. Patient survival after D1 and D2 resections for gastric cancer: long-term results of the MRC randomized surgical trial. Surgical Co-operative Group. Br J Cancer. 1999;79:1522-1530.  [PubMed]  [DOI]
11.  Cuschieri A, Fayers P, Fielding J, Craven J, Bancewicz J, Joypaul V, Cook P. Postoperative morbidity and mortality after D1 and D2 resections for gastric cancer: preliminary results of the MRC randomised controlled surgical trial. The Surgical Cooperative Group. Lancet. 1996;347:995-999.  [PubMed]  [DOI]
12.  Maruyama K, Okabayashi K, Kinoshita T. Progress in gastric cancer surgery in Japan and its limits of radicality. World J Surg. 1987;11:418-425.  [PubMed]  [DOI]
13.  Kodera Y, Sasako M, Yamamoto S, Sano T, Nashimoto A, Kurita A. Identification of risk factors for the development of complications following extended and superextended lymphadenectomies for gastric cancer. Br J Surg. 2005;92:1103-1109.  [PubMed]  [DOI]
14.  Park DJ, Lee HJ, Kim HH, Yang HK, Lee KU, Choe KJ. Predictors of operative morbidity and mortality in gastric cancer surgery. Br J Surg. 2005;92:1099-1102.  [PubMed]  [DOI]
15.  Tokunaga M, Hiki N, Fukunaga T, Ohyama S, Yamaguchi T, Nakajima T. Better 5-year survival rate following curative gastrectomy in overweight patients. Ann Surg Oncol. 2009;16:3245-3251.  [PubMed]  [DOI]
16.  Oh SJ, Hyung WJ, Li C, Song J, Rha SY, Chung HC, Choi SH, Noh SH. Effect of being overweight on postoperative morbidity and long-term surgical outcomes in proximal gastric carcinoma. J Gastroenterol Hepatol. 2009;24:475-479.  [PubMed]  [DOI]
17.  Yamada H, Kojima K, Inokuchi M, Kawano T, Sugihara K. Effect of obesity on technical feasibility and postoperative outcomes of laparoscopy-assisted distal gastrectomy--comparison with open distal gastrectomy. J Gastrointest Surg. 2008;12:997-1004.  [PubMed]  [DOI]
18.  Kulig J, Sierzega M, Kolodziejczyk P, Dadan J, Drews M, Fraczek M, Jeziorski A, Krawczyk M, Starzynska T, Wallner G. Implications of overweight in gastric cancer: A multicenter study in a Western patient population. Eur J Surg Oncol. 2010;36:969-976.  [PubMed]  [DOI]
19.  Physical status: the use and interpretation of anthropometry. Report of a WHO Expert Committee. World Health Organ Tech Rep Ser. 1995;854:1-452.  [PubMed]  [DOI]
20.  Seidell JC, Flegal KM. Assessing obesity: classification and epidemiology. Br Med Bull. 1997;53:238-252.  [PubMed]  [DOI]
21.  Higgins JPT, Green S (editors)..  Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 (updated March 2011). The Cochrane Collaboration. 2011; Available from:  [PubMed]  [DOI]
22.  Guyatt GH, Oxman AD, Vist GE, Kunz R, Falck-Ytter Y, Alonso-Coello P, Schünemann HJ. GRADE: an emerging consensus on rating quality of evidence and strength of recommendations. BMJ. 2008;336:924-926.  [PubMed]  [DOI]
23.  Tierney JF, Stewart LA, Ghersi D, Burdett S, Sydes MR. Practical methods for incorporating summary time-to-event data into meta-analysis. Trials. 2007;8:16.  [PubMed]  [DOI]
24.  Egger M, Davey Smith G, Schneider M, Minder C. Bias in meta-analysis detected by a simple, graphical test. BMJ. 1997;315:629-634.  [PubMed]  [DOI]
25.  Kunisaki C, Makino H, Takagawa R, Sato K, Kawamata M, Kanazawa A, Yamamoto N, Nagano Y, Fujii S, Ono HA. Predictive factors for surgical complications of laparoscopy-assisted distal gastrectomy for gastric cancer. Surg Endosc. 2009;23:2085-2093.  [PubMed]  [DOI]
26.  Tanaka K, Miyashiro I, Yano M, Kishi K, Motoori M, Seki Y, Noura S, Ohue M, Yamada T, Ohigashi H. Accumulation of excess visceral fat is a risk factor for pancreatic fistula formation after total gastrectomy. Ann Surg Oncol. 2009;16:1520-1525.  [PubMed]  [DOI]
27.  Gretschel S, Christoph F, Bembenek A, Estevez-Schwarz L, Schneider U, Schlag PM. Body mass index does not affect systematic D2 lymph node dissection and postoperative morbidity in gastric cancer patients. Ann Surg Oncol. 2003;10:363-368.  [PubMed]  [DOI]
28.  Inagawa S, Adachi S, Oda T, Kawamoto T, Koike N, Fukao K. Effect of fat volume on postoperative complications and survival rate after D2 dissection for gastric cancer. Gastric Cancer. 2000;3:141-144.  [PubMed]  [DOI]
29.  Oh CA, Kim DH, Oh SJ, Choi MG, Noh JH, Sohn TS, Bae JM, Kim S. Impact of body mass index on surgical outcomes in radical total gastrectomy. Hepatogastroenterology. 2012;59:934-937.  [PubMed]  [DOI]
30.  Kim MG, Yook JH, Kim KC, Kim TH, Kim HS, Kim BS, Kim BS. Influence of obesity on early surgical outcomes of laparoscopic-assisted gastrectomy in gastric cancer. Surg Laparosc Endosc Percutan Tech. 2011;21:151-154.  [PubMed]  [DOI]
31.  Ojima T, Iwahashi M, Nakamori M, Nakamura M, Naka T, Ishida K, Ueda K, Katsuda M, Iida T, Tsuji T. Influence of overweight on patients with gastric cancer after undergoing curative gastrectomy: an analysis of 689 consecutive cases managed by a single center. Arch Surg. 2009;144:351-358; discussion 358.  [PubMed]  [DOI]
32.  Tsujinaka T, Sasako M, Yamamoto S, Sano T, Kurokawa Y, Nashimoto A, Kurita A, Katai H, Shimizu T, Furukawa H. Influence of overweight on surgical complications for gastric cancer: results from a randomized control trial comparing D2 and extended para-aortic D3 lymphadenectomy (JCOG9501). Ann Surg Oncol. 2007;14:355-361.  [PubMed]  [DOI]
33.  Pacelli F, Bossola M, Rosa F, Tortorelli AP, Papa V, Doglietto GB. Is malnutrition still a risk factor of postoperative complications in gastric cancer surgery? Clin Nutr. 2008;27:398-407.  [PubMed]  [DOI]
34.  Yasuda K, Inomata M, Shiraishi N, Izumi K, Ishikawa K, Kitano S. Laparoscopy-assisted distal gastrectomy for early gastric cancer in obese and nonobese patients. Surg Endosc. 2004;18:1253-1256.  [PubMed]  [DOI]
35.  Murphy PM, Blackshaw GR, Paris HJ, Edwards P, Barry JD, Lewis WG. Prospective evaluation of nutritional status related to body mass indices and outcomes after modified D2 gastrectomy for carcinoma. Clin Nutr. 2004;23:477-483.  [PubMed]  [DOI]
36.  Kawamura H, Tanioka T, Funakoshi T, Takahashi M. Surgical effects of obesity on laparoscopy-assisted distal gastrectomy. Surg Laparosc Endosc Percutan Tech. 2011;21:155-161.  [PubMed]  [DOI]
37.  Ohno T, Mochiki E, Ando H, Ogawa A, Yanai M, Toyomasu Y, Ogata K, Aihara R, Asao T, Kuwano H. The benefits of laparoscopically assisted distal gastrectomy for obese patients. Surg Endosc. 2010;24:2770-2775.  [PubMed]  [DOI]
38.  Lee HJ, Kim HH, Kim MC, Ryu SY, Kim W, Song KY, Cho GS, Han SU, Hyung WJ, Ryu SW. The impact of a high body mass index on laparoscopy assisted gastrectomy for gastric cancer. Surg Endosc. 2009;23:2473-2479.  [PubMed]  [DOI]
39.  Yoshikawa K, Shimada M, Kurita N, Iwata T, Nishioka M, Morimoto S, Miyatani T, Komatsu M, Mikami C, Kashihara H. Visceral fat area is superior to body mass index as a predictive factor for risk with laparoscopy-assisted gastrectomy for gastric cancer. Surg Endosc. 2011;25:3825-3830.  [PubMed]  [DOI]
40.  Nobuoka D, Gotohda N, Kato Y, Takahashi S, Konishi M, Kinoshita T. Influence of excess body weight on the surgical outcomes of total gastrectomy. Surg Today. 2011;41:928-934.  [PubMed]  [DOI]
41.  Deguchi Y, Fukagawa T, Morita S, Ohashi M, Saka M, Katai H. Identification of risk factors for esophagojejunal anastomotic leakage after gastric surgery. World J Surg. 2012;36:1617-1622.  [PubMed]  [DOI]
42.  Lee SS, Ryu SW, Kim IH, Sohn SS. Impact of gender and body mass index on surgical outcomes following gastrectomy: an Asia-Pacific perspective. Zhonghua Yixve Zazhi (Engl). 2012;125:67-71.  [PubMed]  [DOI]
43.  Bickenbach KA, Denton B, Gonen M, Brennan MF, Coit DG, Strong VE. Impact of obesity on perioperative complications and long-term survival of patients with gastric cancer. Ann Surg Oncol. 2013;20:780-787.  [PubMed]  [DOI]
44.  Moher D, Liberati A, Tetzlaff J, Altman DG. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. Int J Surg. 2010;8:336-341.  [PubMed]  [DOI]
45.  Stevens J, Cai J, Pamuk ER, Williamson DF, Thun MJ, Wood JL. The effect of age on the association between body-mass index and mortality. N Engl J Med. 1998;338:1-7.  [PubMed]  [DOI]
46.  Hawn MT, Bian J, Leeth RR, Ritchie G, Allen N, Bland KI, Vickers SM. Impact of obesity on resource utilization for general surgical procedures. Ann Surg. 2005;241:821-826; discussion 826-828.  [PubMed]  [DOI]
47.  Park CM, Park JS, Cho ES, Kim JK, Yu JS, Yoon DS. The effect of visceral fat mass on pancreatic fistula after pancreaticoduodenectomy. J Invest Surg. 2012;25:169-173.  [PubMed]  [DOI]
48.  El Nakeeb A, Salah T, Sultan A, El Hemaly M, Askr W, Ezzat H, Hamdy E, Atef E, El Hanafy E, El-Geidie A. Pancreatic anastomotic leakage after pancreaticoduodenectomy. risk factors, clinical predictors, and management (single center experience). World J Surg. 2013;37:1405-1418.  [PubMed]  [DOI]
49.  Dhar DK, Kubota H, Tachibana M, Kotoh T, Tabara H, Masunaga R, Kohno H, Nagasue N. Body mass index determines the success of lymph node dissection and predicts the outcome of gastric carcinoma patients. Oncology. 2000;59:18-23.  [PubMed]  [DOI]
50.  Barry JD, Blackshaw GR, Edwards P, Lewis WG, Murphy P, Hodzovic I, Thompson IW, Allison MC. Western body mass indices need not compromise outcomes after modified D2 gastrectomy for carcinoma. Gastric Cancer. 2003;6:80-85.  [PubMed]  [DOI]
51.  Hartgrink HH, van de Velde CJ, Putter H, Bonenkamp JJ, Klein Kranenbarg E, Songun I, Welvaart K, van Krieken JH, Meijer S, Plukker JT. Extended lymph node dissection for gastric cancer: who may benefit? Final results of the randomized Dutch gastric cancer group trial. J Clin Oncol. 2004;22:2069-2077.  [PubMed]  [DOI]
52.  Maurovich-Horvat P, Massaro J, Fox CS, Moselewski F, O’Donnell CJ, Hoffmann U. Comparison of anthropometric, area- and volume-based assessment of abdominal subcutaneous and visceral adipose tissue volumes using multi-detector computed tomography. Int J Obes (Lond). 2007;31:500-506.  [PubMed]  [DOI]
53.  Tokunaga M, Hiki N, Fukunaga T, Ogura T, Miyata S, Yamaguchi T. Effect of individual fat areas on early surgical outcomes after open gastrectomy for gastric cancer. Br J Surg. 2009;96:496-500.  [PubMed]  [DOI]