Obesity improves survival rate of kidney cancer

Although obesity increases the risk of developing kidney cancer, patients with greater body mass index (BMI) seem to have less aggressive disease. BMI, the ratio of weight to height, is a common means of estimating whether someone is overweight or underweight. Although obesity appears to double the risk of developing kidney cancer, also referred to as renal cell carcinoma, there is some evidence that those with a greater BMI at the time of diagnosis may have a better outcome Researchers from the Mayo Clinic, Florida, USA, studied data from 970 patients who underwent surgery for clear cell renal cell carcinoma, the most common type of kidney cancer. Less aggressive tumours were more likely to be found in patients who were considered to be overweight (having a BMI of 25 to 29), or obese (having a BMI 30 or greater), compared with patients who were underweight or normal weight. The 5-year survival rate from kidney cancer was 82 percent for obese patients, 77 percent for overweight patients and 62 percent for normal-weight patients. It was found that compared with normal-weight patients the risk of death from clear cell renal cell carcinoma was reduced by 52 percent for obese patients and by 36 percent for overweight patients. However, the researchers point out that BMI adds little in the way of prognostic information beyond that afforded by available methods. Nevertheless, the relationship between less aggressive tumours and higher BMI needs to be further evaluated to determine if this is due to increased screening and early detection among obese individuals, or if obese patients really do develop less aggressive tumours.