Patients who had gastic-bypass surgery to treat morbid obesity show a dramatically lower risk of cancer than similar patients who didn’t have surgery, Canadian researchers announced Wednesday. The difference was significant in colon and breast cancers, Nicolas Christou, of McGill University in Montreal, said.
The study confirms the findings of two papers issued in August 2007 that showed the surgery reduced overall deaths from cancer.
The new study goes a step further by showing reductions in the incidence of several specific types of cancer, said Philip Schauer, MD, of the Cleveland Clinic Lerner College of Medicine, who was not involved in the study.
In Thursday's news story published in The Los Angeles Times, a bariatric surgeon at Cedars-Sinai Medical Center in Los Angeles was quoted as being skeptical about the findings because cancer takes a long time to develop and the patients were studied for only five years.
He noted that it was now common for weight-loss surgery candidates to undergo mammograms, colonoscopies and endoscopies to screen for cancer before the procedure.
From the LA Times:
Christou and his colleagues compared 1,035 patients who had had bariatric surgery between 1986 and 2002 with 5,746 carefully matched obese patients who had not had the surgery; 81% of the surgery patients had undergone a gastric bypass.
Neither the patients nor the controls had previously been diagnosed with cancer.
Those who underwent the surgery lost an average of 67% of their excess body weight.
In the five years of follow-up, the team observed 21 cancer cases in the surgery group (2%), compared with 487 cases (8.5%) in the control group, Christou told a Washington meeting of the American Society for Metabolic and Bariatric Surgery.
The most dramatic decreases were for breast and colon cancer. The researchers also observed a 70% reduction in pancreatic cancer, a 60% reduction in skin cancer, a 15% reduction in uterine cancer and a 50% reduction in non-Hodgkin's lymphoma, but there were not enough cases of any of these for the results to be statistically significant.
Combined with earlier evidence, Christou said, "the data is pretty convincing" that weight loss reduces the incidence of cancer. "We looked at extreme weight loss, where we were more likely to pick it up. But any weight loss, if it can be maintained, is likely to improve the risk of cancer."