Bariatric surgery may protect against the development of obesity-associated cancer, according to a retrospective study of more than 55,000 people.
After 10 years of follow-up, individuals with obesity who underwent bariatric surgery had about half the risk for developing these malignancies as matched control patients with obesity who did not have surgery.
“This study adds to the building evidence that the significant weight loss associated with bariatric surgery may have a protective effect against cancer formation as well,” said investigator Vibhu Chittajallu, MD, during a press briefing before Digestive Disease Week 2023 (abstract 442).
Dr. Chittajallu, a gastroenterology fellow at Case Western Reserve University and University Hospitals Cleveland Medical Center, and his co-investigators drew the retrospective cohort from the TriNetX multi-institutional database comprising information on more than 107 million patients treated at 47 U.S. healthcare organizations. They identified adults with a body mass index over 35 kg/m2 who did or did not undergo bariatric surgery (or no surgery) and matched them based on risk factors for malignancy formation.
The result, after propensity score matching, was a population of 55,789 patients who underwent bariatric surgery and 55,789 who did not, some of whom also had been diagnosed with cancers associated with obesity, including some GI cancers. The assessment for de novo cancer diagnosis started one year after the index date, which for the study group was the time of bariatric surgery and for the nonsurgical control group was the time of the obesity diagnosis. Patients were followed for up to 10 years.
After 10 years of follow-up, the number of patients who developed obesity-associated cancers was 2,206 among the bariatric surgery cohort compared with 4,960 among those who did not undergo weight loss surgery. The cumulative incidence of obesity-associated de novo cancers at 10 years was 4% versus 8.9%, respectively (hazard ratio [HR], 0.482; 95% CI, 0.459-0.507).
Dr. Chittajallu said the underlying reasons for the observed protection against cancer are unclear, but bariatric surgery is known to decrease excess inflammation and insulin levels and to moderate hormone levels. Fully understanding how these factors could reduce cancer risk will require further study.
Press briefing moderator Loren Laine, MD, the DDW Council Chair and a professor of medicine (digestive diseases) at Yale School of Medicine, in New Haven, Conn., said, “You have to be circumspect when you look at retrospective observational studies” because of the potential influence of factors not recognized or accounted for. “But I think this is great work, and the findings do make sense.”
—Caroline Helwick
Drs. Chittajallu and Lane reported no relevant financial disclosures.
