Breast cancer drug could fight prostate cancer

A new study gives encouraging signs that a hormonal drug used to fight breast cancer might help prevent abnormal prostate growths from turning into cancers. Men who took low doses of the drug toremifene for a year cut their chances of developing prostate cancer roughly in half, doctors reported Saturday at a meeting of the American Society of Clinical Oncology. The findings need to be tested in larger studies, specialists say. But this is the first time any drug has been shown to prevent a precancerous condition from forming a tumor. As many as 50,000 men each year are diagnosed with such growths, and they must then endure constant worry and frequent biopsies to see whether cancer has developed. "Before, we had nothing to offer them. Now you may have something," said Len Lichtenfeld, deputy medical director of the American Cancer Society, which had no role in the research. Toremifene is sold as Acapodene for treating advanced breast cancer. It selectively blocks some of the effects of estrogen, a hormone men have but in much smaller quantities than women. For decades, prostate cancer prevention and treatment has focused on blocking the male hormone testosterone. Targeting estrogen "opens up a new area," said the cancer society's medical director, Harmon Eyre. Prostate cancer is the most common major cancer in the United States. More than 230,000 new cases and about 30,000 deaths from it are expected this year. Men who have abnormal growths called prostatic intraepithelial neoplasia, or PIN, have about a 30% chance of developing prostate cancer within a year and about a 65% chance within two years. The study involved 514 men with the growths at 64 sites across the country who were given either placebos or 20, 40, or 60 milligrams of toremifene for a year. Biopsies were performed at six months and a year after treatment started. Cancer rates were similar among the groups at six months, possibly because initial biopsies had missed some cases that were found the second time around. But after a year, 24.4% of those on the drug had developed cancer versus 31% of those on placebos. That means that for every 100 patients who took the drug for a year, seven cancers were prevented, Price said. The benefit was greatest for those who took the lowest dose for a full year. Their cancer risk was 48% lower than it was for men who didn't get the drug. A larger study testing the lowest dose is enrolling 1,500 men now. If it confirms that the drug can prevent prostate cancer, it would be "an important step" because there's little agreement now about how to treat the disease once it's found, said Peter Greenwald, director of cancer prevention at the National Cancer Institute. Two years ago, a huge study showed that a testosterone-blocking drug called finasteride cut the risk of developing prostate cancer by 25% in men at high risk of the disease because of family history or other factors. Toremifene would be the first drug to prevent progression to cancer once abnormalities had appeared. (AP)