Investigators have found that men who are or have been overweight or who have high insulin levels are more likely to die from prostate cancer.

The discovery of these two predictors is important, because doctors now have two crucial clues as to which patients will develop the most life-threatening tumors and therefore which to treat most aggressively.

In the recent study, researchers sliced and diced the data from the Physician's Health Study, which followed more than 22,000 male doctors in the United States from 1982 onward. Participants who were overweight or who had high insulin levels (as measured by a protein, C-peptide, that rises along with the concentration of insulin in the body) were four times more likely to die of prostate cancer.

"Roughly about 10 percent of [those afflicted with prostate cancer] will eventually die of the cancer," said Jing Ma, the study's lead researcher. "The crucial question now facing urologists, oncologists and prostate cancer patients is, what are the risk factors that can predict the bad cancers?"

Prostate cancer, which grows very slowly, is the second-leading cause of death among malignancies in men, the first being lung cancer. There are more than 186,000 cases of prostate cancer annually in America.

Men should learn from the study that extra weight not only contributes to heart disease and diabetes but somehow encourages the deadliness of prostate cancer, said Ma, who works with the Brigham and Women's Hospital and Harvard University in Boston. "This gives more incentive to control body weight for men in general, and specifically for men with prostate cancer," he said.

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