Study findings and key details

For the study, researchers analyzed data from 21,837 patients who had undergone bariatric surgery between 1982 and 2018 and compared them to the same number of age, sex, and BMI-matched controls who had not undergone surgery. Information was taken from the Utah Population Database, the Utah Cancer Registry, and three Utah bariatric surgery registries.

Among the patients, 79% were female, and both groups had an average BMI of around 46 at the beginning of the study. Follow-up periods ranged from 2.8 and 13.5 years.

Overall, the researchers found that patients who had bariatric surgery had a 25% lower risk of developing any kind of cancer and a 37% lower risk of obesity-related cancers compared to patients in the non-surgical group. Cancer mortality was also 43% lower in the surgical group.

This reduction in risk was largely found in female patients. Women who received bariatric surgery were 41% less likely to develop obesity-related cancer, including breast, ovarian, uterine, and colon cancer. They also had a 47% reduction in mortality for any kind of cancer, including a 55% reduction for obesity-related cancers and a 38% reduction for non-obesity-related cancers.

Among men, bariatric surgery was not associated with a reduced risk of developing cancer, but it was linked to 51% lower mortality from non-obesity-related cancers.

According to the researchers, the type of bariatric surgery a patient received also affected their cancer mortality risk. Cancer mortality was significantly lower among patients who received gastric bypass surgery compared to those who received gastric banding or sleeve gastrectomy. The sample size for a duodenal switch was too small to compare to gastric bypass.

Ted Adams, an adjunct professor of internal medicine at the University of Utah and one of the study's authors, noted that a hormonal mechanism may contribute to why bariatric surgery was able to significantly reduce obesity-related cancers, particularly among women. Currently, researchers are studying whether other factors, such as chronic inflammation, increased release of steroid hormones, or high blood glucose from insulin resistance may also contribute to cancer risk in patients with obesity.

Commentary

According to David Voellinger, a bariatric surgeon at Novant Health, the study highlighted the potential benefits of weight loss in treating cancer.

"Bariatric surgery can be used to not only decrease the incidence of certain cancers but also decrease the mortality associated with them," Voellinger said. "Also, primary care physicians and oncologists should look more closely at weight loss and bariatric surgery as tools for treating cancer."

Similarly, Mir Ali, a bariatric surgeon and medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center, said the study suggests that "there are many long-term benefits of weight loss surgery," including ones that may not be as obvious, such as reducing cancer risk.

"This study may help people who meet the criteria for surgery but are still hesitant to take that step see the additional scope of benefits," Ali added.

According to Anton Bilchik, a surgical oncologist, chief of medicine, and the director of the gastrointestinal and hepatobiliary program at Saint John's Cancer Institute at Providence Saint John's Health Center, future studies should also see "if similar long-term benefits occur in patients who undergo medical treatment with some of the newer drugs such as Ozempic and Mounjaro." (The Obesity Society, Medical Xpress, 8/22; Hollowell, Becker's Hospital Review, 8/28; Lennon, Medical News Today, 8/27; Adams et al., Obesity, 8/22)

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