Merck Prostate Cancer Medicine Merits More Attention

Researchers urged doctors to discuss with patients the benefits of Merck & Co.’s Proscar for preventing prostate cancer, after a study found that prescribing of the product didn’t increase when a 2003 trial showed the medicine wards off tumors.

The drug, also sold generically as finasteride, was shown to reduce some men’s risk of developing prostate cancer by a quarter, to 18 percent from 24 percent, in a trial described in the New England Journal of Medicine in July 2003. Over the next two years, there was no increase in finasteride prescriptions aimed at preventing that disease, according to today’s report in the journal Cancer Epidemiology, Biomarkers & Prevention.

Doctors’ failure to prescribe more of the medicine may have resulted in more cases of prostate cancer, said Ian M. Thompson, lead author of the 2003 study and chairman of the department of urology at the University of Texas Health Science Center, in San Antonio. If men over the age of 55 with certain risk factors were given finasteride, diagnoses of prostate cancer in the U.S. would shrink by 40,000 to 60,000 a year, he said.

“There are no other proven ways of reducing your risk of prostate cancer -- this is the only one,” said Thompson, who wasn’t involved in the study released today. If people at risk took the medicine, “tens of thousands wouldn’t be diagnosed” or get sick, he said in a telephone interview yesterday. Risk factors include being black, having a family history, being over the age of 65, or showing elevated levels of prostate-specific antigen, or PSA, according to today’s study.

Cause of Death

The National Cancer Institute estimates that 217,730 men in the U.S. will be diagnosed with prostate cancer this year and that about 32,000 will die of it. The disease is the second- leading cause of cancer death in American men, after lung cancer, according to the American Cancer Society, based in Atlanta.

The new study, by doctors at the Veterans Health Association in Durham, North Carolina; Duke University School of Medicine in Durham; and the University of Toronto offers several explanations why physicians seven years ago didn’t act on the data on finasteride. The research was funded by the Department of Veterans Affairs and the Defense Department.

While the results, which were based on a study called the Prostate Cancer Prevention Trial, showed reduced risk for the disease overall, there was also evidence that finasteride might raise the some men’s likelihood of developing aggressive tumors.

Subsequent research showed these worries were overstated, according to the new study. Three articles published since 2003 “suggest finasteride does not increase the risk of high-grade disease,” the authors wrote. “The rate of true high-grade disease may have been lower” among men taking finasteride.

‘Chemoprevention’

Concerns about aggressive tumors weren’t the only reason physicians failed to prescribe the drug more. Doctors and patients at that time weren’t familiar with the idea of “chemoprevention,” or the use of drugs to stave off cancer, said Linda Kinsinger, one of the new study’s authors and chief consultant for preventive medicine at the VHA.

“It’s not surprising that doctors didn’t all jump on the bandwagon to prescribe finasteride because it is unclear to what extent we are ready for preventive medications,” Kinsinger said in a telephone interview yesterday. “We don’t yet have the tools to predict very well who will develop cancer. There should be more discussion between patients and doctors about potential benefits and downsides of the drug.”

“Prevention is not reimbursed very well in medicine and doctors are paid basically to treat cancer, but we are seeing a gradual increase in interest,” Thompson said.

Hair Growth

Finasteride, which is most commonly prescribed to shrink an enlarged prostate and to facilitate urination, is also the active ingredient in Propecia, a hair-growth product sold by Whitehouse Station, New Jersey-based Merck. The dose for prostate treatment is 5 milligrams, compared with 1 milligram for hair growth.

Merck’s sales for Proscar were about $291 million in 2009, and sales of Propecia that year came to about $440 million, according to the company’s annual filing. For the six months ended June 30, sales for Proscar fell 25 percent from a year earlier to $114.1 million, according a company filing. The drug is also widely available in generic form.

Merck gained 41 cents, or 1.2 percent, to $35.77 at 4:01 p.m. in New York Stock Exchange composite trading.

Generic Finasteride

Sales of the generic finasteride were $186 million and 5.1 million prescriptions of the drug were filled in 2009, according to data compiled for Bloomberg by IMS Health Inc., of Norwalk, Connecticut.

“We don’t know if the 1 milligram dosage reduces the risk, but my gut feeling says that there would be some reduction,” Thompson said. Taking a higher dosage wouldn’t increase hair growth, he said.

The study released today asked 325 urologists and 1,200 general physicians who prescribed finasteride in 2006 whether they gave patients the drug for chemoprevention. Some 64 percent of the urologists and 80 percent of the general physicians didn’t prescribe for that purpose, according to the study.

Neither physicians nor patients appear to be worried about side effects from finasteride, Thompson said.

“The worst side effect of finasteride is growing more hair,” he said.

To contact the reporter on this story: Arielle Fridson in New York at afridson@bloomberg.net.

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