Cancer Risk Slashed After Bariatric Surgery

WASHINGTON, D.C., June 2008

Calling this a "very exciting finding," lead researcher Nicolas Christou, MD, PhD, director of bariatric surgery and professor of surgery at McGill University in Montreal, said that "hopefully subsequent studies will shed more light on [this subject]."

Being overweight or obese raises the risk of several types of cancer including breast, colon, esophageal and kidney, according to the American Cancer Society. Every year 500,000 Americans die of cancer, and one-third of these deaths is linked to diet, lack of physical activity and being overweight, the group states.

Exactly how weight loss surgery reduces cancer risk is not fully understood, Christou says. "A lot of cancer risk is genetic, and we don't alter a person's genetic," he says. "Is it hormonal? We don't know."

Perhaps, he speculates, "it is the inability to eat a 16-ounce porterhouse steak that is barbequed with carcinogens," he says. Many cancer-causing chemicals or carcinogens are created during cooking. Consuming large amounts of red meat has also been linked to certain cancers. Weight loss surgery patients are unable to eat large volumes of food, due to the decreased size of their stomach following surgery.

In the study, bariatric surgery patients were 78 percent less likely to develop any cancer, when compared with their equally overweight counterparts who did not undergo weight loss surgery. Bariatric surgery patients had an 83 percent reduction in their risk for developing breast cancer and a 68 percent reduction in risk of developing colorectal cancer, when compared with their counterparts who did not have surgery.

Reductions were also seen in risk for other, more rare cancers such as pancreatic cancer, endometrial cancer, kidney cancer, myeloma, melanoma and non-Hodgkin's lymphoma among those participants who underwent weight loss surgery; however, these reductions were not statistically significant, Christou said.

The Canadian Bariatric Cohort Study compared 1,035 bariatric surgery patients with 5,746 controls who were matched for body mass index and did not undergo surgery to lose weight. They were tracked for a maximum of five years. None of the study participants had a history of cancer. During the study period, two percent of people in the surgery group were diagnosed with cancer, compared with 8.5 percent of participants who did not have bariatric surgery.