The Impact of Bariatric Surgery on Cancer Incidence

Albert B. Lowenfels, MD


December 21, 2018

What is the impact of bariatric surgery on cancer incidence? To answer this question, the authors of a study published in the British Journal of Surgery[1] compared cancer frequency following various types of obesity surgery in 8794 obese patients in England (average age, 42 years) who were operated versus in an equal number of nonoperated patients.

During a median follow-up period of 55 months, the risk for hormone-related cancers was significantly reduced in the operated group compared with the nonoperated group (odds ratio [OR], 0.23; 95% confidence interval [CI], 0.18-0.30). In contrast, for colorectal cancer following gastric bypass (but not banding or sleeve gastrectomy), there was an overall increase in the risk for colorectal cancer (OR, 2.63; 95% CI, 1.17-5.95).

Gastric Bypass Increased the Risk for Colorectal Cancer

This report provides valuable information about cancer risk following bariatric surgery, one of the most common procedures performed by general surgeons. The risk reduction for hormonally dependent cancers was seen in both males (prostate) and females (breast, endometrium), and the benefit became more pronounced with increasing duration of follow-up. On the basis of a total of 16 patients with colorectal cancer, gastric bypass resulted in a more than twofold increased risk.

If confirmed with studies with longer follow-up and more patients, the findings in this report suggest that the age for screening for colorectal cancer following bariatric surgery should be lowered. One study weakness is that the dataset only listed obesity as a comorbidity and did not include actual information to calculate body mass index. Nevertheless, the results seem biologically plausible and are consistent with those from other research reports.

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