But the discovery, arising from a new analysis of a large federal study, comes with a debate: Should men take the drug?

Prostate cancer is unlike any other because it is relatively slow-growing and while it can kill, it often is not lethal. In fact, most leading specialists say, a major problem is that men are getting screened, discovering they have cancers that may or may not be dangerous, and opting for treatments that can leave them impotent or incontinent.

So should healthy men take a drug for the rest of their lives to avoid getting and being treated for a cancer that, in most instances, it would be better to leave undiscovered and untreated?

Some prostate cancer experts say the answer is yes. Any man worried enough about prostate cancer to be screened might consider it, they say.

The drug, finasteride, is available as a generic for about $2.00 a day, and millions of men safely take it now to shrink their prostates, its approved use.

With finasteride, as many as 100,000 cases of prostate cancer a year could be prevented, said Dr Eric Klein, director of the Center for Urologic Oncology at the Cleveland Clinic.

Dr Howard Parnes, chief of the prostate cancer group at the National Cancer Institute’s division of cancer prevention, also is convinced. “There is a tremendous public health benefit for the use of this agent,” he said.

Other experts say, Not so fast. Finasteride might not make much of a difference in the death rate because so few men die from prostate cancer. What the drug’s proponents are advocating is taking a drug to somehow compensate for what many believe is the nation’s overzealous diagnosis and treatment of the disease.

Dr Peter Albertsen, a prostate cancer specialist at the University of Connecticut, explains: While 10 per cent of men 55 and older find out they have prostate cancer, the cancer is lethal in no more than 25 per cent of them. So if finasteride reduced the prostate cancer’s incidence by 30 per cent, about 7 per cent of men would get a cancer diagnosis and approximately 1.8 per cent instead of 2.5 per cent would have a lethal cancer.

“Finasteride might make a difference, but only in a very small subset of men,” Albertsen said.