What is the risk of gastric bypass surgery leading to colon cancer?

Negative risk!: Obesity is a major risk factor for many kinds of cancer due to inflammatory hormones and chemicals. After gastric bypass, the risk of colon (and other) cancers wil decrease. So the risk is actually negative. In patients who had cancer, the strategy of bariatric surgery is sometimes used right after chemo and tumor removal.

Risk factors: Risk factors for colon cancer include smoking, obesity, high fat diet, high red meat diet, low fiber diet, history of polyps, family history of colon cancer. I am not aware of gastric bypass surgery increasing the risk of colon cancer, but the need for gastric bypass surgery suggests that some risk factors mentioned above are likely present.