A hormonal drug used to fight breast cancer might help prevent abnormal prostate growths from turning into cancers.
A new study found that men who took low doses of the drug Toremifene for a year, cut their chances of developing prostate cancer in half.
Doctors say the signs are encouraging, but the findings now need to be tested in larger studies.
The news is exciting as this is the first time any drug has been shown to prevent a precancerous condition from forming a tumour.
As many as 50,000 men in the U.S. each year are diagnosed with such growths, and then suffer constant worry and frequent biopsies to see whether cancer has developed.
Dr. Len Lichtenfeld, deputy medical director of the American Cancer Society, which had no role in the research, says before this discovery there was nothing to offer such men.
Toremifene, brand name Acapodene, is used for treating advanced breast cancer. It selectively blocks some of the effects of estrogen, a hormone men have in much smaller quantities than women.
Prostate cancer prevention and treatment has focused for many years on blocking the male hormone, testosterone.
Dr. Harmon Eyre,the cancer society's medical director, says targeting estrogen opens up a new area.
Prostate cancer is the most common major cancer in the United States and more than 230,000 new cases and about 30,000 deaths from it are expected this year.