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Obese patients who undergo stomach surgery to lose weight may reduce their risk of developing some cancers by as much as 80 per cent, according to a study by Canadian researchers that provides new evidence eating less could play a critical role in warding off the disease.
The findings reinforce the idea that people may be able to control their risk of cancer through diet and lifestyle, and the study is one of the first to look at the role played by bariatric surgery.
"Weight-loss surgery can be used as a means of preventing cancer from developing and killing these patients," said Nicolas Christou, the study's lead author and director of bariatric surgery at McGill University. "Even modest weight loss, especially if it can be maintained, might impact positively on their cancer risk."
The study was presented yesterday at the American Society for Metabolic and Bariatric Surgery's annual meeting in Washington.
In addition to losing weight, patients who had bariatric surgery also reduced their consumption of carcinogens that may be present in some foods, Dr. Christou says. That decrease means patients may have reduced their overall exposure to toxins that could contribute to the risk of developing cancer, he said.
Bariatric surgery is the only effective treatment for morbid obesity, according to the World Health Organization, and is usually performed using one of two different techniques. One focuses on reducing the size of the patient's stomach alone, leading to decreased food intake. The second also reroutes food through the intestines, allowing fewer calories to be absorbed.
The study is one of the first pieces of medical research to highlight a possible link between weight-loss surgery and decreased risk of cancer, and could provide critical clues in the fight against the disease, said David Lau, president of Obesity Canada, a not-for-profit organization.
"I think the study results really confirm what we already know about obesity surgery, that it really saves lives, and now we know that obesity surgery, in the appropriate individual, can also help to reduce the cancer risk," said Dr. Lau, who is also chairman of the Diabetes and Endocrine Research Group at the University of Calgary.
"We are just starting to understand the relationship between obesity and many forms of cancer, and this is a very active area of investigation and research right now," added Dr. Lau, who was not involved in the study.
In the study, researchers compared 1,035 patients who had had bariatric surgery from 1986 to 2002 with 5,746 patients who did not undergo the procedure over a five-year period. Researchers matched patients in both groups by age, gender and the duration of the morbidly obese diagnosis to ensure an accurate comparison.
They found that 21 bariatric patients, or 2 per cent, were diagnosed with cancer in the five-year period following surgery, compared with 8.5 per cent of those who did not have the procedure.
People who had bariatric surgery were 85 per cent less likely to develop breast cancer than those who did not, according to the study, while the risk of colon cancer was reduced by 70 per cent. After the five-year follow-up period was over, 12 bariatric surgery patients had been diagnosed with breast cancer, compared with 362 in the non-surgery group. Meanwhile, two bariatric surgery patients were diagnosed with colon cancer, compared with 35 in the non-surgery group.
Researchers also found reductions in the incidence of pancreatic, skin and uterine cancer, as well as non-Hodgkin's lymphoma among the surgery group, but the number of cases was not considered statistically significant.
Patients who had bariatric surgery lost 67 per cent of their excess body weight, on average, according to the study.
Dr. Christou said the study provides strong evidence that the benefits of bariatric surgery extend beyond weight loss and Canadian policy makers should work to make it more accessible. "The perception that we have has to change," he said. "[We] need to reprioritize."
With a report from Avis Favaro and Elizabeth St. Philip of CTV News
