Researchers at Brigham and Women’s Hospital (BWH) have found that the prostate specific antigen (PSA) cancer screening test is falsely lowered by a factor of two in middle-aged men who have taken Propecia (finasteride), a hair-loss drug used by more than 4 million men worldwide, for one year. These findings were published on Dec. 5, in Lancet Oncology online
“For these men, the PSA level needs to be corrected, or the detection of prostate cancer may not occur until it is more aggressive,” said Anthony D’Amico, Harvard Medical School professor of radiation oncology, chief of genitourinary radiation oncology at BWH, and lead author of the study. “It is also important to note that because PSA becomes a more accurate indicator for cancer presence when taking finasteride-containing drugs like Propecia, changes in PSA as low as 0.3 ng/ml in one year have been used to recommend a prostate biopsy.”
PSA is a protein produced by the prostate gland and is often elevated in the presence of prostate cancer and other prostate disorders. A blood test to measure PSA is the most effective test available for the early detection of prostate cancer, and levels are reported as nanograms of PSA per milliliter of blood (ng/ml). Controversy exists as to what is considered a normal PSA level, but a high PSA level and the rise in PSA levels over time may indicate that cancer is present and a biopsy is necessary.
In this study, researchers aimed to determine whether Propecia, which is a 1 mg. formulation of finasteride, has a similar effect on PSA levels as Proscar, a 5 mg. formulation of the drug used in the treatment of enlarged prostate. Previous studies have shown Proscar to significantly decrease PSA levels. The researchers studied 355 men aged 40 to 60 years old for 48 weeks in a placebo-controlled, randomized, double-blind study. Participants’ PSA levels were obtained at the start of the study and once every 12 weeks for the duration of the study. Researchers found that for men who received 1mg/day of finasteride in an analogous fashion to Proscar, PSA levels dropped by a factor of two in one year. As a result of this decrease, researchers recommend that men between 40 and 60 years of age who take Propecia for hair loss have their PSA levels adjusted by a factor of 2 just as they would if they were taking Proscar.