Weight loss surgery may reduce cancer risk
26 June 2009
The take-home message is that weight loss through less drastic measures such as healthy eating and exercise could also help to reduce cancer risk. 
Dr Julie Sharp, Science Information Manager, Cancer Research UK
Weight loss (bariatric) surgery that results in sustained weight loss may help to reduce cancer risk in obese women, according to a new Swedish study published in The Lancet Oncology.
Obesity is a strong risk factor for various types of cancer, and losing weight is thought to help reduce this risk. The new study looked at whether weight loss surgery (such as gastric banding or gastric bypass) is more effective in reducing cancer risk than standard treatments for weight loss (ranging from advanced lifestyle advice to no treatment).
The study used data on cancer rates taken from the ongoing Swedish Obese Subjects trial, which was designed to assess the effect of long-term weight loss on disease and death rates in obese people. The trial compared around 2000 people who had weight loss surgery with a similar number receiving standard treatment. Those people who had surgery had a sustained average weight loss of 19.9 kg over 10 years, while those who had standard treatment put on an average of 1.3 kg.
The study found that five to six out of every 100 women who had weight loss surgery developed cancer during the study period, while about nine out of every 100 women who had standard treatment developed the disease.
However, there was no difference in the number of men who developed cancer after weight loss surgery: six to seven out of every 100 men developed cancer, whether they had surgery or standard treatment. However, this could be because there may have been too few men in the study for there to be any noticeable effect. It may also be that weight loss has more effect on hormone-sensitive cancers - such as breast and endometrial cancer, which affect more women.
While the researchers found that weight loss surgery had a beneficial effect on cancer risk in women, they couldn't find a clear relationship between the amount of weight lost or level of food intake and the reduced risk. There are a number of possible theories as to why the weight loss associated with surgery may decrease cancer risk. Further investigation is needed with more people and over a longer period of time in order to draw firmer conclusions.
Commenting on the study, Dr Julie Sharp, Science Information Manager at Cancer Research UK said:
"This study provides some evidence that losing weight can help people to reduce their cancer risk. While this research looked at people who lost weight through surgery, the take-home message is that weight loss through less drastic measures such as healthy eating and exercise could also help to reduce cancer risk."
Dr Karen Woo, Bupa's Associate Medical Director warned that weight loss surgery carries a number of risks: "There may be quite serious physical and psychological consequences of having weight loss surgery," she commented. "For these reasons bariatric surgery should not be considered lightly. Anyone considering a surgical intervention for weight loss should have the opportunity to discuss it with their GP and to have access to support, counselling, dietician and specialist bariatric surgical consultation."
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Related information
- Gastric band operation health factsheet
- Gastric bypass surgery health factsheet
- Obesity in adults health factsheet
- BMI calculator
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