Belly fat, weight cycling ups kidney cancer risk

NEW YORK - Postmenopausal women who are overweight or obese appear to have a greater risk of developing, renal cell carcinoma, a common form of kidney cancer, and study findings suggest that a larger waist girth and a history of weight loss and regain further increase this risk.

"Our study suggests that the risk of renal cell carcinoma can be lowered if overweight individuals lose excess central body fat and then maintain stable weight at a more desirable level," Dr. Juhua Luo, of Karolinska Institutet, Stockholm, Sweden told Reuters Health.

Luo and colleagues analyzed data from more than 140,000 U.S. women, aged 50 to 79 years, enrolled in the Women's Health Initiative study.

They compared associations between the development of renal cell carcinoma, a cancer of the lining of the kidney, and the women's body weight and frequency of weight loss and regain (weight cycling) over an average of 7.7 years.

The findings are published in the American Journal of Epidemiology.

Overall, obese women with a body mass index (BMI) at or above 35, had a 60 percent excess risk of renal cell carcinoma compared with women of normal weight (BMI less than 25), the researchers note. This risk increased 3 percent for every unit increase in BMI.

When the investigators analyzed abdominal obesity as an independent risk factor they found that each 0.1-unit increase in waist-to-hip ratio increased the risk of developing renal cell carcinoma by 24 percent.

Moreover, women with a history of 10 or more weight cycles had more than double the risk of developing renal cell carcinoma, compared with women who held a steady weight over the study period, the investigators note.

The researchers say their findings provide further evidence that obesity, particularly central adiposity, is associated with increased risk of developing renal cell carcinoma, and that a history of weight cycling may further increase this risk among postmenopausal women.

SOURCE: American Journal of Epidemiology, October 20, 2007.