Information about the increased risk of high-grade prostate cancer diagnoses associated with the use of finasteride and dutasteride has been added to the prescribing information for the two 5-alpha reductase inhibitors, which are approved to treat benign prostatic hyperplasia, the Food and Drug Administration announced on June 9.
These labeling changes are the result of the FDA’s review of two randomized studies, which evaluated the impact of 5-alpha reductase inhibitors (5-ARIs) in reducing the risk of prostate cancer when taken daily in 27,000 men aged about 50 years and older who were considered at an increased risk of developing prostate cancer. The Prostate Cancer Prevention Trial (PCPT) evaluated daily use of finasteride 5 mg versus placebo for 7 years, and the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) trial evaluated daily use of dutasteride 0.5 mg versus placebo for 4 years. In those two studies, the risk of being diagnosed with prostate cancer was significantly reduced among those randomized to either of the two drugs, compared with those on placebo. But the reduction was because of a lower rate of lower-grade prostate cancers (with a Gleason score of 6 or lower). The risk of higher grade prostate cancers (with a Gleason score of 8-10) was increased among those who received one of the two 5-ARIs.
"This risk appears to be low, but health care professionals should be aware of this safety information, and weigh the known benefits against the potential risks when deciding to start or continue treatment with 5-ARIs in men," according to the statement.
Before prescribing one of these drugs, the statement advises that health care professionals "perform appropriate evaluation to rule out other urological conditions, including prostate cancer, [which] might mimic" benign prostatic hyperplasia (BPH).
The information has been added to the warnings and precautions section of the labels for 5-ARIs. Dutasteride is marketed as Avodart and is also available in combination with tamsulosin (Jalyn). Finasteride is marketed as Proscar (5-mg dose, for BPH) and Propecia (1-mg dose, approved for treating male pattern hair loss). None of these products is approved to prevent or reduce the risk of prostate cancer.
The results of these studies were the focus of a meeting of the FDA’s Oncologic Drugs Advisory Committee in December 2010. Citing the increases in high-grade prostate cancers among the treated men in these studies, the majority of the panel voted that the two drugs, when used as chemopreventive agents for reducing the risk of prostate cancer, had an unfavorable risk-benefit profile.