June 16, 2008
Drug Said to Cut Risk of Prostate Cancer by 30%
By Gina Kolata
For the first time, leading prostate cancer specialists say they have a drug that can significantly cut men's risk of developing the disease, dropping the incidence by 30 percent.
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? Is it worth risking a chance that unanticipated side effects may emerge years later if millions of men with no prostate problems take the drug?
Some prostate cancer specialists 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 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.
While it might seem convoluted to offer a drug to prevent the consequences of overtreatment, that is the situation in the country today, others say. Preventing the cancer can prevent treatments that can be debilitating, even if the cancers were never lethal to start with.
"That's the bind we're in right now," said Dr. Christopher Logothetis, professor and chairman of genitourinary medical oncology at M.D. Anderson Cancer Center in Houston. "Most of the time, treatment wouldn't help and may not be necessary. But the reality is that people are being operated on."
"We are trying to avoid a diagnosis to avoid a prevention whose value is disputed," he said. With finasteride, Logothetis added, "we're trying to overcome our other sins."
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 percent of men 55 and older find out they have prostate cancer, the cancer is lethal in no more than 25 percent of them. So if finasteride reduced prostate cancer's incidence by 30 percent, about 7 percent of men would get a cancer diagnosis and approximately 1.8 percent instead of 2.5 percent would have a lethal cancer.
"Finasteride might make a difference, but only in a very small subset of men," Albertsen said.
And, he adds, the study did not look for a decline in death rates, and it is unlikely that any study ever will - it would take too long and be too expensive. Yet the ultimate goal of prevention is to save lives. It remains an assumption that finasteride would have much effect on the minority of prostate cancers that, despite early detection and treatment, still kill.
Finasteride blocks the conversion of testosterone to dihydrotestosterone, a hormone active mostly in the prostate and the scalp and that all prostate cancers need to grow. The drug is available from Merck, as Proscar, and from six companies as a generic to shrink the prostate in older men, whose prostates can enlarge, making urination difficult.
Researchers say it turns out that shrinking the prostate also may be good for cancer detection by making it easier to find all tumors, including the most aggressive.
"The data are compelling," said Dr. Peter Scardino, chairman of the department of surgery at Memorial Sloan-Kettering Cancer Center in New York, a convert who originally thought the drug was dangerous. "Finasteride has to be recognized as the first clearly demonstrated way to prevent prostate cancer with any medication or any oral agent at all."