FRIDAY, Jan. 22, 2010 (HealthDay News) -- Obesity increases the risk of developing a common and virulent form of kidney cancer, a new study finds.
Researchers looked at 1,640 patients, average age 62, with kidney tumors and found that obese patients were 48 percent more likely to develop a clear-cell renal cell cancer (RCC) than those with a body-mass index(BMI) of less than 30, the cutoff for obesity. The odds of developing RCC increased by 4 percent for every extra BMI point.
Malignant tumors with clear-cell RCC were found in 67 percent of obese patients with malignant tumors, compared with 57 percent of non-obese patients with malignant tumors. Obese and non-obese patients had similar rates for other kinds of malignant tumors, including papillary, chromophobe and collecting duct.
"We also looked at other health and lifestyle factors, like diabetes, hypertension and smoking. This showed that the only other factors that were independent predictors of clear-cell RCC were male gender and tumor size," study author Dr. William T. Lowrance, of the Memorial Sloan-Kettering Cancer Center in New York City, said in a news release.
He and his colleagues concluded that BMI is an independent predictor of clear-cell RCC and that the odds of having clear-cell RCC increase as BMI increases.
The study was published in the January issue of the journal BJUI.
"A number of studies have suggested that obesity could be a risk factor for RCC, but the exact reason is unknown. Researchers suggest it might be secondary to hormonal changes, decreased immune function, hypertension or diabetes in obese patients," Lowrance said.
The American Cancer Society has more about kidney cancer.