New research appearing in the Sept. 20 issue of the Journal of Clinical Oncology has found that drugs frequently used to treat prostate cancer may significantly increase the risk of developing heart disease and diabetes.

Researchers from Harvard Medical School examined data collected on more than 70,000 men with prostate cancer from the 1990s through 2002 being treated with gonadotropin-releasing hormone (GnRH) agonist drugs. Previous studies had suggested that prostate cancer patients taking the drugs gained excess weight around the abdomen and became resistant to insulin.

The Harvard researchers wanted to determine if such weight gain affected the patients' risk of heart disease and diabetes, and found that men taking the drugs experienced a 44 percent increased risk of developing diabetes, were 16 percent more likely to develop heart disease, and 11 percent more likely to have a heart attack or die from heart failure.

GnRH agonist drugs have become standard therapy for treating prostate cancer -- which is the second-most common cancer in men, after skin cancer, and kills more than 27,000 in the United States every year. They have become widely used in men whose prostate cancer may not benefit from their use.

"Given the number of people on these drugs and the fact that some of these men may not necessarily be getting any benefit, I think it's a bit concerning," says the study's lead author, Nancy L. Keating, who urges doctors to be "more cautious" in prescribing the drugs.

Natural health advocates say many cases of prostate cancer can be prevented or reversed without toxic cancer drugs, by using natural food treatments such as pomegranate juice, curry, cauliflower and capsaicin -- the compound that makes jalapeno peppers hot -- as well as omega-3 fatty acids.