Bariatric surgery was associated with fewer incidences of new colorectal lesions in patients undergoing bariatric surgery compared with a control group not undergoing bariatric surgery, according to researchers from University of Virginia, Charlottesville, VA.
Although obesity is a known risk factor for colorectal cancer and could lead to the development of pre-cancerous, colorectal polyps, it is not known whether bariatric surgery results in a decreased risk of subsequent colonic neoplasia. In the paper, ‘Bariatric surgery is independently associated with a decrease in the development of colorectal lesions’, published in Surgery, the researchers theorised that surgery would decrease the risk of developing new cancer and precancerous polyps
The researchers reviewed all patients (n=3,676) who underwent bariatric surgery (gastric bypass, sleeve gastrectomy or gastric banding) at the their institution between 1985-2015. These patients were matched to patients with obesity (controls) who did not have bariatric surgery (n=46,873) from an institutional data repository. The cases/controls were propensity score matched 1:1 by demographics, comorbidities, BMI and socioeconomic factors. The matched cohort was then compared by univariate analysis and conditional logistic regression.
The results revealed that a total of 4,462 patients (2,231 per group) were included in the analysis with a median follow-up of 7.8 years. There were no no statistically significant baseline differences in initial BMI (48 vs 49), sex and age in addition to other comorbidities (all p> 0.05). Unsurprisingly, patients in the bariatric surgery group had more weight loss (55.5% vs -1.4% decrease in excess BMI, p<0.0001) but the researchers also found they developed fewer colorectal lesions (2.4% vs 4.8%, p< 0.0001). However, the researchers reported no differences in polyp characteristics or staging for patients who developed cancer (all p>0.05). Finally, after risk adjustment, bariatric surgery was independently associated with a decrease in new colorectal lesions (p=0.016).
“Bariatric surgery was associated with lesser, risk-adjusted incidence of new colorectal lesions in this large population of propensity matched patients undergoing bariatric surgery compared with a control group not undergoing bariatric surgery,” the authors concluded. “These results suggest the benefits of bariatric surgery may extend beyond weight loss and mitigation of comorbidities.”