Bariatric surgery for weight loss appears to protect obese women from developing uterine cancer, according to a large retrospective study presented at the Society of Gynecologic Oncology (SGO) Annual Meeting on Women’s Cancer, held March 22–25 in Tampa, Florida. The study found that obese women who underwent bariatric surgery had a 71% lower risk of developing uterine cancer than obese women who did not, and the risk was reduced by 81% if the weight loss was maintained postsurgery.

Modifiable Risk Factor

Approximately 95% of all uterine cancers are endometrial, and roughly half of cases of endometrial cancer are thought to be due to obesity; obese women are two to four times more likely to develop endometrial cancer than their normal-weight counterparts.

“Obesity is the second leading cause of preventable death in the United States, and it appears to be a modifiable risk factor for uterine cancer,” said Kristy Ward, MD, senior gynecologic oncology fellow in the Department of Reproductive Medicine at the University of California, San Diego, School of Medicine and Moores Cancer Center.

“We found that the risk of uterine cancer decreased after bariatric surgery. This research adds to the growing evidence that reducing obesity reduces cancer risk. We need to emphasize the importance of helping women lose weight, and bariatric surgery may be an option for appropriately selected patients,” Dr. Ward said.

Guidelines for referral to bariatric surgery include a well-informed, motivated patient who is severely obese (body mass index ≥ 40 kg/mg²), has acceptable surgical risk, and has failed to achieve adequate weight loss by other means. Bariatric surgery is also suitable for people with body mass index ≥ 35 kg/m² who have either diabetes, obstructive sleep apnea, obesity-related cardiomyopathy, or severe joint disease. About 200,000 people undergo bariatric surgery annually. The study did not analyze different types of bariatric surgery, she said.

Study Findings

The retrospective study was based on the University Health System Consortium database of more than 7.4 million women aged 18 and older and admitted to any of 392 academic medical center hospitals or affiliated hospitals between January 1, 2009, and June 1, 2013. Mean age was 52.6 years; 56.6% were white, 21.3% were black, 8.5% were Hispanic, and 2.7% were Asian or South Pacific Islander. The study controlled for two variables: a history of bariatric surgery and presence of obesity.

Among all admissions, 103,797 had undergone bariatric surgery and 44,345 had a history of uterine cancer. Among women who did not have a history of bariatric surgery, the rate of uterine malignancy was 599 per 100,000, and the rate was 2.8 times higher among obese than nonobese women: 1,409 per 100,000 vs 496 per 100,000, respectively.

Looking at patients with a history of bariatric surgery, the risk of uterine malignancy was 408 per 100,000. The rate remained high among women who had persistent obesity, while it was much lower in women who were no longer obese: 682 per 100,000 vs 270 per 100,000, respectively.

Among all obese patients, bariatric surgery conferred a 71% risk reduction in uterine cancer compared with no bariatric surgery. Women who had the surgery and were not currently obese had an 81% risk reduction in uterine cancer compared with those who did not have bariatric surgery. Women who had the surgery but were obese had a 52% reduced risk of ovarian cancer compared with those who did not have the surgery. ■

Disclosure: Dr. Ward reported no potential conflicts of interest.

Reference

1. Ward KK, Ronancio AM, Shah NR, et al: Bariatric surgery decreases the risk of uterine malignancy. SGO Annual Meeting on Women’s Cancer. Abstract 4. Presented March 22, 2014.