WEDNESDAY, July 8, 2009 (HealthDay News) -- Doctors don't have to be so cautious in prescribing the drug finasteride to men at risk for prostate cancer, a new study suggests.
Physicians face a dilemma when trying to decide whether to use the drug, which has been shown to prevent prostate cancer in about one in five men who take it. However, findings from the Prostate Cancer Prevention Trial published in 2003 concluded that men who developed prostate cancer while taking finasteride were 25 percent more likely to develop an aggressive form of the disease.
But a new study from the Stanford University School of Medicine suggests that the drug does not increase the risk for aggressive prostate cancer but simply makes it easier to diagnose. The study appears in the July 7 issue of Clinical Cancer Research.
The Stanford team suspected a flaw in the analysis of data in the 2003 study, rather than a problem with the drug. To test this theory, they analyzed data on 1,304 men who'd had an abnormal digital rectal exam or high PSA test results and had been referred to Stanford. None of the men was taking finasteride. Prostate cancer was eventually diagnosed in nearly 500 of the men, including 247 who had aggressive, high-grade cancer.
Finasteride shrinks the prostate, making malignancies easier to detect, the researchers said. And the smaller the prostate, the more likely a biopsy would yield a diagnosis of high-grade cancer, they said, and the more likely a high PSA level would predict the disease. For example, the diagnostic rate for one level of high-grade cancer was 29.7 percent in men with prostates between 20 to 29.9 cubic centimeters, compared with 6.5 percent for men with prostates larger than 80 cubic centimeters.
"We're showing that this is all related to size" of the prostate, Dr. Joseph Presti Jr., a research professor in urology and director of the urologic oncology program at Stanford, said in a news release from the university.
The authors of the 2003 study reached similar conclusions after they analyzed their own results, according to Catherine Tangen, statistical principal investigator for the first study. The findings of the new study "are consistent with everything we found," Tangen said in the news release.
Men should be given the opportunity to take finasteride if they and their doctors feel it's necessary, she added.
The U.S. National Cancer Institute has more about prostate cancer.