The increased risk of cancer in obese women appears to be reduced by weight-loss or “bariatric” surgery, according to a report in the Journal of the American College of Surgeons.

Severely “obese women are at incredible risk for multiple cancers, primarily breast and (uterus) cancer but also colorectal and other gynecologic cancers,” Dr. Susan C. Modesitt from University of Virginia Health System, Charlottesville, told Reuters Health by email. “I hope that physicians begin to be proactive in evaluating these women for cancer promptly when indicated.”

Modesitt and colleagues studied 1482 severely obese women who underwent bariatric surgery at the University of Virginia and compared them with a population of severely obese women who did not undergo surgery.

Overall, 53 bariatric surgery patients (3.6 percent) developed cancer, including 15 with breast cancer and 9 with uterus cancer, the authors report.

Most cases were diagnosed and treated before bariatric surgery (34 women, 64.1 percent), while 32 percent (17 women) were diagnosed after bariatric surgery.

Women with severe obesity who had not undergone bariatric surgery had a significantly higher cancer diagnosis rate (5.8 versus 3.6 percent) than did the patients who had undergone bariatric surgery.

“Although not conclusive,” the authors explain, “the fact that most of our women with bariatric surgery were diagnosed before their operation and the fact that fewer bariatric patients were diagnosed with cancer compared with their obese counterparts may lend support to the hypothesis that bariatric surgery could be protective for obesity-related cancers.”

“The hard part is knowing whether weight loss in these women will translate into a decrease in their risk for cancer, and we are trying to start to answer those questions by evaluating multiple factors both pre- and post-bariatric surgery,” Modesitt said.

“Unfortunately, diet and exercise have not proven very effective strategies for weight loss in this population, which has prompted the explosion in bariatric surgery.”

SOURCE: Journal of the American College of Surgeons, June 2009.