FDA, Merck Update on Proscar, PSA and Prostate Cancer

Washington, DCThe FDA has approved labeling changes to Proscar (Finasteride) regarding the drug's effects on Prostate Specific Antigen (PSA) and the use of PSA in Prostate Cancer Detection.

The new labeling was done to reflect the fact that treatment with Proscar reduces serum PSA concentrations by roughly 50 percent within six months of treatment and that this decrease is predictable over the entire range of PSA values in patients with symptomatic benign prostatic hyperplasia (BPH).

Therefore, a new baseline PSA should be established in men taking Proscar, and patients should be monitored periodically while on treatment, as the decrease in serum PSA can occur in the presence of prostate cancer.

Further, the FDA warning states that "men aged 55 and over with a normal digital rectal examination and PSA greater than or equal to 3.0 ng/mL at baseline taking finasteride 5 mg/day in the 7-year Prostate Cancer Prevention Trial (PCPT) had an increased risk of Gleason score 8-10 prostate cancer."

In June 2011, the FDA issued a warning that Propecia is linked to an increased risk of high-grade prostate cancer. That warning was based on a study involving Avodart and Proscar. Propecia has one-fifth the active ingredient as Proscar, leading the FDA to determine that Propecia should carry the same warning about the risk of high-grade prostate cancer. High-grade prostate cancer is a rare but more aggressive cancer than low-grade prostate cancer.