Weight-loss surgery may reduce cancer risk in women

The study highlights that weight-loss surgery such as stomach stapling significantly reduces the incidence of cancer in obese women.

In their research, the Swedish researchers observed that women who had their stomachs stapled not only shed their extra pounds, but also were 42 percent less likely to get cancer than those who did not. However, the surgery did not show the same effect in men.

How the research was conducted
To reach their findings, Swedish researchers followed 2,010 obese patients (1420 women and 590 men) for 10 years after they had their stomachs stapled. They also tracked 2,037 people who were obese but did not undergo the procedure.

All the study participants, who were between the ages of 37 to 60 years, were eligible for bariatric (weight-loss) surgery. The decision to go under the knife was based on patient choice.

For patients who had the surgery, most lost 19.9 kilograms over ten years, while the people who did not have the surgery, most gained an average of 1.3 kg.

Of women who got their stomachs stapled, 79 got cancer. In the non-surgery group, 130 women got cancer.

"In our study, the significant reduction in overall cancer incidence in the female surgery group emanated from a variety of cancer types, indicating a broad effect of bariatric surgery," the study authors wrote.

Among the men, 38 of the surgery group got cancer compared to 39 in the other group.

The findings baffled the researchers as to why only women, not men, have lower cancer risk after the Bariatric surgery, the surgical treatment of morbid obesity.

"There is an unknown factor behind this effect, but we have no idea what it is," said lead researcher Lars Sjostrom of Sahlgrenska University Hospital in Sweden.

Sjostrom and colleagues observed no associations between weight loss without surgery or reduced calorie intake and cancer incidence in either men or women. He said the possibility could be that “the beneficial effects of bariatric surgery on cancer are mediated by mechanisms other than weight loss or reduced energy intake.”

It has long been thought that obese people have a higher cancer risk, possibly because fat cells propel hormones that might lead to the disease.

"This is one more piece of evidence in a complex puzzle," said Dr. Len Lichtenfeld of the American Cancer Society.

About bariatric surgery
Bariatric surgery, also known as weight loss surgery, is a medical procedure to treat severe obesity, a chronic condition that is difficult to treat through diet and exercise alone.

The procedure includes the gastric bypass procedure as one of the numerous operations. The operation is an option for people who are severely obese and cannot lose weight by traditional means or who suffer from serious obesity-related health problems.

The SOS study findings are published in the June 24 online issue of the medical journal, The Lancet Oncology.