Long-term
results from a major federal study ease worries about the safety of a
hormone-blocking drug that can lower a man's chances of developing prostate
cancer. The drug cut prostate cancer
risk by 30 percent without raising the risk of dying of an aggressive form of
the disease as earlier results hinted it might.
The new work could prompt a fresh look at using the drug for cancer
prevention. Experts say it could prevent tens of thousands of cases each year,
saving many men from treatments with seriously unpleasant side effects.
The drug is
sold as Proscar by Merck & Co. and in generic form as finasteride to treat
urinary problems from enlarged prostates. It's also sold in a lower dose as
Propecia to treat hair loss. A decade
ago, the drug was found to cut the risk of prostate cancer. But there was a
small rise in aggressive tumors among its users. Some researchers said that by
shrinking the prostate, the drug was just making these tumors easier to find in
a biopsy sample — not causing them. But
the concern led the Food and Drug Administration to turn down the drug for
cancer prevention and warnings were added to its label.
Now, with 18
years of follow-up from that earlier study, researchers report that men on the
drug were no more likely to die than those not taking it. That's reassuring because if the drug were
truly spurring lethal tumors, there would have been more deaths among its users
as time went on, said Dr. Michael LeFevre, a family physician at the University
of Missouri.
LeFevre
wrote an editorial that appears with the study in Thursday's New England
Journal of Medicine. He is one of the leaders of the U.S. Preventive Services
Task Force, an independent panel of doctors who advise the federal government.
The group has not taken a stance on finasteride for prevention but has advised
against screening with PSA blood tests.
Screening
does more harm than good, the panel has said, because although 240,000 new
prostate cancers are diagnosed each year in the United States, only about
30,000 prove fatal. That means many men are treated for cancers that grow too
slowly to be life-threatening, and often suffer sexual and urinary problems as
a result.
The study,
led by Dr. Ian Thompson at the Cancer Therapy and Research Center in San
Antonio, was done to see whether finasteride could lower the risk of prostate
cancer in men who were getting screened with annual PSA blood tests, as many
still choose to do.
Researchers
assigned 18,882 men 55 or older with no sign of prostate cancer on blood tests
or a physical exam to take finasteride or dummy pills for seven years. When the
study ended, those who had not been diagnosed with prostate cancer were offered
biopsies to check for hidden signs of the disease.
For the new
analysis, researchers tracked the study participants for a longer time — 18
years in all since enrollment began. Only about 10 percent of men on
finasteride developed prostate cancer versus 15 percent of those on dummy
pills. Aggressive tumors were found in 3.5 percent of men on the drug versus 3
percent of the others. Yet 78 percent of both groups were alive after 15
years. That means the drug cannot be
recommended to prolong life, just to ease suffering by preventing disease,
LeFevre said. "You may be preventing cancers that don't need to be
prevented" because so few are life-threatening, but screening is finding
these tumors anyway and leading to unnecessary treatments, he said. Reducing
that number is a valid reason to use a prevention drug, he said.
Finasteride's
other impact is financial. Proscar and a similar drug, GlaxoSmithKline PLC's
Avodart, cost about $4 a pill. Generic finasteride is available for less.
Insurers cover it when prescribed to treat urinary problems but may not pay if
it's used solely for cancer prevention.
The drug
also can cause hot flashes, fatigue, weakness, low sex drive and trouble having
sex. "A man certainly needs to know
what he's getting into if he decides to take this," LeFevre said
http://abcnews.go.com/Health/wireStory/drug-safely-cuts-prostate-cancer-risk-study-finds-19962459