The effect of bariatric surgery on reducing the risk of colorectal cancer: a meta-analysis of 3,233,044 patients

Outcomes of Metabolic and Bariatric Surgery in Populations with Obesity and Their Risk of Developing Colorectal Cancer: Where Do We Stand? An Umbrella Review on Behalf of TROGSS-The Robotic Global Surgical Society

Introduction: Obesity is a chronic disease associated with increased risk for several cancers, including colorectal cancer (CRC), a leading cause of cancer-related mortality. The majority of CRC cases are associated with modifiable risk factors. Metabolic and bariatric surgery (MBS) is a proven, durable, and successful intervention for obesity. This study aimed to evaluate the impact of MBS on CRC risk through measures of association, such as relative risk (RR) and odds ratio (OR). Methods: A systematic search of PubMed, Scopus, Web of Science, ScienceDirect, and Embase was conducted to identify systematic reviews (SR) and meta-analyses examining the relationship between obesity treated with MBS and CRC incidence. The PICO framework guided inclusion criteria, and three independent reviewers screened articles using Rayyan software. Quality assessment was performed using AMSTAR2. Results: Of 1336 screened articles, 10 SR met inclusion criteria, encompassing 53,452,658 patients. Meta-analyses consistently showed a significant reduction in CRC risk following MBS in patients with severe obesity. Risk reductions were reported by Liu et al. (RR: 0.46, 95% CI: 0.32-0.67, p < 0.01), Chierici et al. (RR: 0.46, 95% CI: 0.28-0.75, p = 0.018), Wilson et al. (RR: 0.69, 95% CI: 0.53-0.88, p = 0.003), and Pararas et al. (RR: 0.56, 95% CI: 0.40-0.80, p < 0.001). Sensitivity analyses supported these findings. For colon cancer, Liu and Chierici both reported an RR of 0.75 (95% CI: 0.46-1.21, p = 0.2444) with significant heterogeneity (I2 = 89%). A trend towards reduced rectal cancer risk (RR: 0.74, 95% CI: 0.40-1.39, p = 0.3523) was noted but limited by fewer studies. Sex-specific analyses revealed protective effects in both sexes, with a more pronounced impact in females (RR: 0.54, 95% CI: 0.37-0.79, p = 0.0014). Conclusions: This umbrella review synthesizes current evidence on the impact of MBS on CRC risk, highlighting a consistent protective association. The findings also indicate a potential risk reduction for both colon and rectal cancer, with a more pronounced effect observed among females compared to males. Given the profound implications of MBS on cancer incidence, morbidity, and mortality, further high-quality, long-term studies are essential to deepen our understanding and optimize its role in cancer prevention and patient care.

Laparoscopic sleeve gastrectomy as a bridge to colorectal cancer surgery for obese patients: a case report

BACKGROUND

Severe obesity greatly influences the difficulty of colorectal cancer surgery and has been reported to prolong operative time, increase the rate of laparotomy, and elevate increase postoperative complications. We investigated the efficacy of laparoscopic sleeve gastrectomy (LSG) for preoperative weight loss to ensure safe colorectal cancer surgery.

CASE PRESENTATION

A 51 year-old female with a body mass index of 43.5 kg/m2 was referred to our hospital due to a positive fecal occult blood test. She was diagnosed as having a laterally spreading tumor of the cecum by colonoscopy. Endoscopic submucosal dissection was attempted but proved difficult due to the size of the lesion and its proximity to the appendiceal orifice. We planned bariatric surgery prior to colorectal surgery, and she underwent LSG without any complications. Seven months after the LSG, she had lost 30.7 kg, and her final preoperative body mass index was 27.8 kg/m2. Single-incision laparoscopic ileocecal resection was then performed safely. The pathological diagnosis was adenocarcinoma in adenoma of the cecum, TisN0M0.

CONCLUSION

LSG was effective in reducing visceral fat and making it possible to perform safe surgery for colorectal cancer in a severely obese patient.

Clinical significance of colonoscopy before laparoscopic bariatric/metabolic surgery in Japanese patients

PURPOSE

Obesity is known to be associated with colorectal adenoma (CRA) and colorectal cancer (CRC); yet colonoscopy is not considered an essential preoperative evaluation before bariatric/metabolic surgery. The aim of this study was to clarify the clinical significance of preoperative colonoscopy for obese Japanese patients.

METHODS

The subjects of this retrospective study were 114 patients who underwent screening colonoscopy before bariatric/metabolic surgery. Multivariate analyses were performed to evaluate the independent predictors of CRA/CRC among the characteristics identified as significant or nearly significant by univariate analyses.

RESULTS

Colonoscopy revealed abnormal findings indicating the need for biopsy or polypectomy in 20 of the 114 patients (17.5%), and CRA was diagnosed in 13 patients (11.4%). Three patients (2.6%), who were all ≥ 56 years old, had a CRA ≥ 10 mm in diameter. The multivariate analysis showed that older age and male sex were significant predictors of CRA/CRC, which was identified in 46.2% of the male patients aged ≥ 46 years.

CONCLUSION

Our findings suggest that older age and male sex may be risk factors for CRA/CRC in obese Japanese candidates for bariatric/metabolic surgery; thus, preoperative colonoscopy should be considered for these high-risk patients.

Risk reduction of non-hormonal cancers following bariatric surgery

Metabolic and bariatric surgery (MBS) is the most effective intervention for weight loss leading to significant resolution of obesity-related medical conditions. Recent literature has demonstrated risk reduction of certain cancer types after MBS. Studies have shown an overall reduction in the risk of hormonal cancer, such as breast and endometrial cancer. However, the association between bariatric surgery and the incidence of various types of non-hormonal cancer such as esophageal, gastric, liver, gallbladder, colorectal, pancreatic and kidney cancer remains contested. The aim of this study was to highlight obesity and its relationship to cancer development as well as bariatric surgery and its role in cancer reduction with focus on non-hormonal cancers.

The Impact of Bariatric Surgery on the Incidence of Colorectal Cancer in Patients with Obesity-a Systematic Review and Meta-analysis of Registry Data

PURPOSE

Cancer and obesity represent two of the most significant global health concerns. The risk of malignancy, including colorectal cancer (CRC), increases with obesity. The aim of this study was to perform a systematic review and meta-analysis to determine the value of bariatric surgery in reducing CRC risk in patients with obesity using registry data.

MATERIALS AND METHODS

A systematic review and meta-analysis were performed as per PRISMA guidelines. The risk of CRC was expressed as a dichotomous variable and reported as odds ratios (OR) with 95% confidence intervals (CIs) using the Mantel-Haenszel method. A multi-treatment comparison was performed, examining the risk reduction associated with existing bariatric surgery techniques. Analysis was performed using RevMan, R packages, and Shiny.

RESULTS

Data from 11 registries including 6,214,682 patients with obesity were analyzed. Of these, 14.0% underwent bariatric surgery (872,499/6,214,682), and 86.0% did not undergo surgery (5,432,183/6,214,682). The mean age was 49.8 years, and mean follow-up was 5.1 years. In total, 0.6% of patients who underwent bariatric surgery developed CRC (4,843/872,499), as did 1.0% of unoperated patients with obesity (54,721/5,432,183). Patients with obesity who underwent bariatric surgery were less likely to develop CRC (OR: 0.53, 95% CI: 0.36-0.77, P < 0.001, I2 = 99%). Patients with obesity undergoing gastric bypass surgery (GB) (OR: 0.513, 95% CI: 0.336-0.818) and sleeve gastrectomy (SG) (OR: 0.484, 95% CI: 0.307-0.763) were less likely to develop CRC than unoperated patients.

CONCLUSION

At a population level, bariatric surgery is associated with reduced CRC risk in patients with obesity. GB and SG are associated with the most significant reduction in CRC risk.

PROSPERO REGISTRATION

CRD42022313280.

Does Bariatric Surgery Reduce the Risk of Colorectal Cancer in Individuals with Morbid Obesity? A Systematic Review and Meta-Analysis

Bariatric surgery has shown to be effective in producing sustained weight loss and the resolution of obesity related medical problems. Recent research focused on the role of obesity and adipose tissue in tumorigenesis, finding a strong crosslink through different mechanisms and highlighting an increase in cancer incidence in individuals with obesity. The aim of this meta-analysis is to find if bariatric surgery reduces the incidence of colorectal cancer in patients with obesity. We performed a meta-analysis including 18 studies (PROSPERO ID: CRD4202235931). Bariatric surgery was found to be significantly protective toward colorectal cancer incidence in individuals with obesity (HR: 0.81, p = 0.0142). The protective effect persisted when considering women (RR: 0.54, p = 0.0014) and men (RR: 0.74, p = 0.2798) separately, although this was not significant for the latter. No difference was found when comparing Roux-en-Y gastric bypass and sleeve gastrectomy. Bariatric surgery reduces the incidence of colorectal cancer in individuals with obesity independently from gender and surgical procedure. Prospective large cohort studies are needed to confirm these findings.