M. Kwak1, J. H. Mehaffey1, R. B. Hawkins1, B. Schirmer1, C. L. Slingluff1, P. T. Hallowell1, C. M. Friel1 1University Of Virginia,Department Of Surgery,Charlottesville, VA, Virgin Islands, U.S.
Introduction:
While bariatric surgery has demonstrated excellent long-term weight loss results, little is known about secondary effects such as cancer risk. Previous studies have shown obesity is a risk factor for colorectal cancer and possibly precancerous colorectal polyp formation, but it is unclear whether bariatric surgery could potentially mitigate this risk. We hypothesized that bariatric surgery would decrease the risk of developing colorectal lesions (defined as new development of colorectal cancer and precancerous colorectal polyps).
Methods:
All patients (n=3,676) who received bariatric surgery (gastric bypass, sleeve gastrectomy, or gastric banding) at a single institution (1985-2015) were included in the study. Additionally, obese patients (n=46,873) from an institutional data repository were included as controls. Cases and controls were propensity score matched 1:1 by demographics, comorbidities, BMI, and socioeconomic factors. The matched cohort was compared by univariate analysis and conditional logistic regression.
Results:
A total of 4,462 patients (2,231 per group) with a median follow-up of 7.8 years were well matched with no significant baseline differences in BMI (49 vs 48 kg/m2, p=0.26), Female gender (51% vs 50%, p=0.16), and Age (43 vs 43 years old, p=0.63) as well as other comorbidities (all p>0.05). The surgical cohort had significantly more weight loss (55.5% vs -1.4% Reduction in Excess Body Mass Index, p<0.0001). The surgical cohort developed significantly fewer colorectal lesions (2.4% vs 4.8%, p<0.0001). There were no significant differences in polyp characteristics or staging for patients who developed cancer (all p>0.05). After risk-adjustment, bariatric surgery was independently associated with reduction in new colorectal lesions (OR 0.62, 0.42-0.91, p=0.016, Table).
Conclusion:
Bariatric surgery was associated with lower risk-adjusted incidence of new colorectal lesions in this large population. These results are encouraging that the benefits of bariatric surgery may extend beyond weight loss and comorbidity mitigation.
