Finasteride Cuts Prostate Cancer Risk; No Lifespan Impact
The generic drug finasteride indeed reduces the risk of prostate cancer in men by at least about one-third, but has no impact on their lifespans, according to results of an 18-year follow-up study published online today in The New England Journal of Medicine.
Finasteride reduced the risk of prostate tumors by about 30%, and the risk of low-grade tumors even more, by 43%, the study showed.
“If you look at the number of prostate cancers that are diagnosed annually and multiply that by 30%, that’s the number of cancers we might be able to prevent each year,” Ian M. Thompson Jr., M.D., the study leader and director of the Cancer Therapy and Research Center (CTRC) at The University of Texas Health Science Center at San Antonio, said in a statement. “That’s more than 71,000 men. That’s more than 175 jumbo jets full of men who won’t get cancer, who won’t face treatments with side effects like sexual dysfunction.”
However, while the drug reduced the risk of prostate cancer among those prescribed with the drug in the trial of 19,000 men, a slightly higher percentage of those on finasteride developed high-grade cancer than those taking a placebo, though the difference shrank in the follow-up analysis.
The finding led the FDA in 2011 to add a warning to the drug’s label about the increased risk of diagnosis with high-grade prostate cancer. That in turn sparked additional studies, which ultimately concluded finasteride made the tumors easier to find by shrinking the prostate and making the PSA test work better.
The Prostate Cancer Prevention Trial began in 1993, funded by a National Cancer Institute (NCI) grant. The 18-year follow-up study compared survival in both men taking finasteride and men taking placebo, to see if there was an increased risk of death in men who took the drug.
Results from the follow-up study showed no impact on either overall survival or survival after prostate cancer diagnosis. The men in the finasteride study arm had a median age of 62 and took the drug for seven years.
The follow-up study was coordinated by SWOG, an international network of research institutions led by Dr. Thompson and consisting of more than 4,000 researchers at more than 500 U.S. institutions including 24 NCI-designated cancer centers, as well as cancer centers in almost a dozen other countries. Formerly known as Southwest Oncology Group, SWOG’s goals include improving the practice of medicine in preventing, detecting, and treating cancer, as well as enhancing the quality of life for cancer survivors.