Finasteride: Are the Risks Worth it?

Does finasteride prevent prostate cancer? No — it just prevents you from knowing that you have it, says Patrick C. Walsh, M.D., who worries that men taking this drug might be dealing with bad information. Even worse, he adds, taking finasteride might mask the signs of aggressive curable prostate cancer until much later.

“Many of my patients have asked me about an article that was in the New York Times,” says Walsh, University Distinguished Service Professor of Urology. The article appeared on the newspaper’s front page on Sunday, June 15, 2008, and the spin on finasteride — that it somehow helps men by preventing them from knowing they have prostate cancer, so they can avoid the potential side effects of treatment — was, in Walsh’s opinion, a disaster.

The trouble with finasteride, he says, actually dates back to 2003, when the original article was published in the New England Journal of Medicine. The authors of that article studied 18,000 men who randomly were assigned to receive either 5 mg of finasteride (then used mainly to treat benign enlargement of the prostate; men also use it under the trade name Propecia as a treatment for hair loss) or a placebo. The men in the finasteride group had a 25-percent lower risk of being diagnosed with prostate cancer — but a 68-percent higher risk of being diagnosed with high-grade disease (a Gleason score of 7 to 10; this kind of cancer is generally more difficult to cure). “Since then, the authors have tried to erase these results and encourage urologists to prescribe finasteride for prostate cancer prevention,” says Walsh. “When these attempts failed, they recently decided to approach patients and physicians directly.”

No Decrease in Positive Biopsies

In this study, for the first seven years, men underwent a biopsy if they had an abnormal finding on a digital rectal exam, or if their PSA became elevated. But because this was a double blind study, men on finasteride did not know that their PSA levels were artificially low.

For this reason, fewer men on the drug who were told to have a biopsy followed that advice. Were there fewer cancers in these men because finasteride actually prevents cancer, or because fewer men got a biopsy in the first place? “Were they fooled by their low PSA levels into thinking they couldn’t possibly have cancer?” Yes, says Walsh. In this study, 15 percent fewer men on finasteride underwent a biopsy “because they were lulled into a false sense of security by their low PSA,” he continues. “Thus, the major effect of this drug was to keep men from knowing that they even needed a biopsy.” Of the men in the study who actually underwent a biopsy, the frequency of positive biopsies for cancer was statistically the same in the men on placebo and the men on finasteride.

“ If men want to prevent prostate cancer, finasteride is the last thing they should take. All it can do is prevent them from knowing that they may have lethal disease, until it may be too late to cure.”

Walsh is very concerned about the increase in high-grade disease, and the possibility, also expressed by others, that this “presents an unacceptable risk for a form of treatment that has little or no value.”

Among finasteride’s critics is Stewart Justman, who wrote a book called Do No Harm — How a Magic Bullet for Prostate Cancer Became a Medical Quandary, which Walsh recently reviewed for the New England Journal of Medicine. “Whether the drug actually causes high-grade disease or merely helps find it,” says Walsh, “the fact remains that when men on finasteride are diagnosed with prostate cancer, they are more likely to have dangerous, high-grade disease.”

He believes the “real harm here is that many men will be lulled into a false sense of security. If you are told that you’re on a drug that will prevent cancer, and your PSA falls, you aren’t going to be on your guard.” Walsh wants men taking finasteride to know that if their PSA — no matter how low it is — begins to go up at all, they need to have a biopsy right away, “because their risk of having cancer is three times higher than for men without a rising PSA, and because they are six times more likely to be diagnosed with high-grade disease.”

Will the Real PSA Number Please Stand Up?

If you are taking finasteride, you need to be able to determine your actual
PSA number.
If you have been taking the drug for:

Two years: Multiply your PSA by 2,
Between two and seven years: Multiply your PSA by 2.3
More than seven years: Multiply your PSA by 2.5

If your PSA begins to rise: Get a biopsy immediately. Your risk of having
cancer is three times higher than that
of men without a rising PSA, and your risk of having high-grade cancer is six times higher.

Risky Business

Recently, Walsh has seen this risk in action twice, in two patients “who thought they were okay,” but weren’t. They had been taking Propecia (a form of finasteride that’s used to restore hair loss) for 10 years. “One man had a PSA of 3.8, and the other had a PSA of 4,” Walsh explains. But because finasteridelowers PSA levels, a little math is needed to figure out the true PSA number (see box), “and these men actually had PSA levels between 9 and 10. Both of them had high-grade prostate cancer, Gleason 8 disease, that had spread outside the prostate. One of them had a positive surgical margin.”

Walsh, who has spent his career working to save lives from prostate cancer, through better treatment combined with earlier diagnosis, is greatly troubled by the recent push for men to take finasteride. “I am very concerned about encouraging patients and general physicians to use this drug,” he says. “First, it has no primary effect in reducing the number of men who will have a positive biopsy. Second, men will believe that it prevents cancer, will be pleased that their PSA levels fall, and will not understand the potential danger they’re in — of undiagnosed high-grade disease.”

As a treatment for BPH, finasteride is fine, Walsh says, as long as men who are being screened for prostate cancer understand the guidelines (see box). “If men do not want to know if they have prostate cancer,” he continues, “they should just avoid PSA testing.

This will save them $730 a year (the cost of finasteride), and will avoid the increased risk of high-grade disease. If they want to prevent prostate cancer, finasteride is the last thing they should take. All it can do is prevent them from knowing that they may have lethal disease, until it may be too late to cure.”



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