Link Between Bariatric Surgery and Colorectal Cancer Risk Evaluated in New Study

Undergoing weight loss surgery may decrease an individual’s risk of colorectal cancer, according to the findings of a new study.

Bariatric surgery was associated with lower rates of developing colorectal cancer, according findings published this month in the medical journal JAMA Surgery.

Generally, obesity increases the risk of many types of diseases, such as diabetes and high blood pressure, as well as certain cancers, including colorectal cancer. Therefore, in this new study French researchers set out to determine what effect weight loss surgery had on the risk of colorectal cancer specifically.

To do so, they conducted a population based multi-center nationwide cohort study in France from 2009 to 2018, using the French national health insurance information system database.

The risk of colorectal cancer was estimated using standardized incidence ratios for more than 1 million patients with obesity ages 50 to 75 years. Patients who did not undergo bariatric surgery were followed for five years. Those who did undergo the procedure were followed for six years.

Roughly 74,000 subjects underwent adjustable gastric banding, sleeve gastrectomy, or gastric bypass surgery and 975,000 patients did not undergo bariatric surgery.

During gastric banding a surgeon places a silicone band around the top of the stomach to decrease the size. In gastric bypass the stomach is stapled to be smaller and the intestine is connected to it. With sleeve gastrectomy, roughly 80% of the stomach is surgically removed. All are considered forms of bariatric surgery.

Overall, more than 13,000 patients were diagnosed with colorectal cancer. Incidence rates of cancer were higher for patients who did not undergo surgery.

Patients who underwent surgery had an incidence rate of colorectal cancer of 0.6%. Comparatively, the group that did not undergo surgery had an incidence rate of 1.3%.

People who are obese have a 34% higher risk of colon cancer than the general population. Any type of weight loss surgery can reduce the risk back to normal.

An editorial which accompanied the study emphasized the findings did not prove cause and effect, but merely an association between the two. People considering weight loss surgery should weigh their options based on available evidence and discuss the risks and benefits with their doctor.

The results of bariatric surgery can vary widely and lead to adverse health effects. Studies have indicated revision surgery is more common after gastric banding surgery and it can increase a person’s risk of chronic opioid use. It can also increase a person’s risk of suicide.