Weight-loss surgery can cut cancer risk

Successful bariatric surgery allows morbidly obese patients to lose up to 70 percent of their excess weight and to maintain weight loss. The latest study by Dr. Nicolas Christou of the McGill University Health Centre (MUHC) and McGill University shows that this surgery also decreases the risk of developing cancer by up to 80 percent. Dr. Christou presented his preliminary results yesterday at the 25th Annual Meeting of the American Society for Metabolic & Bariatric Surgery.

The researchers compared 1,035 morbidly obese patients who underwent bariatric surgery at the MUHC between 1986 and 2002 with 5,746 patients with the same weight profile who did not undergo the operation. The number of cancer diagnoses in first group was 85 percent lower for breast cancer and 70 percent lower for colon and pancreatic cancers, and was also distinctly lower for several other types of cancer.

"The relationship between obesity and many forms of cancer is well established," said Dr. Christou. "This is one of the first studies to suggest that bariatric surgery might prevent the risk of cancer for a significant percentage of morbidly obese people."

Obesity affects the body in multiple ways, so a single hypothesis cannot fully explain these results, say the researchers. However, excess body fat is widely thought to be responsible for increased hormone production, a major risk factor for breast and colon cancer. Thus so modifications to the patient's hormonal metabolism due to weight loss might explain the lower incidence of these cancers in patients who underwent surgery.

"Bariatric surgery is an extremely efficient tool in the treatment of morbid obesity and its consequences, and the MUHC is one of Canada's leaders in this field." Dr. Christou said. "We're hoping that these results will help the government and public health authorities realise the importance of this procedure in the fight against the various pathologies associated with obesity."

(Source: McGill University Health Centre: June 2008)