BOSTON, Nov. 12 (UPI) -- Men who are overweight or obese when diagnosed with prostate cancer are nearly twice as likely to die after treatment, a U.S. study found.

Dr. Jason Efstathiou, of Massachusetts General Hospital in Boston, and colleagues tracked 788 patients with locally advanced prostate cancer for more than eight years and found being overweight or obese at the time of diagnosis was a unique, independent risk factor for death from prostate cancer.

Compared to men with normal BMI of less than 25, men with BMI between 25 and 30 were more than 1.5 times more likely to die from their cancer, while men with BMI of 30 were 1.6 times more likely to die from their disease compared to men with normal range BMI.

The study, published in the journal Cancer, found that after five years the prostate cancer mortality rate for men with a normal BMI was less than 7 percent compared to about 13 percent for men with BMI of 25.