Dr. John Trachtenberg of the Princess Margaret Hospital in Toronto said he hoped the drug, called abarelix, might also be a more effective treatment for prostate cancer, although he stressed it was too early to tell.
Prostate cancer is the biggest cancer killer of men in the Western world after lung cancer.
More than 180,000 cases of prostate cancer will be diagnosed in U.S. men this year and nearly 32,000 men will die of it. About 85 percent of patients have hormone-dependent prostate cancer. They can be treated by cutting off testosterone, either by removing the testicles, where the hormone is produced, or by using a drug to block production. But, Trachtenberg said, using drugs to block testosterone often first causes levels of the hormone to surge. Half got abarelix and half got TAP Pharmaceuticals' Lupron, a standard treatment.