DALLAS -- As low-dose Propecia (finasteride) stimulates hair growth for male pattern baldness, it appears to suppress prostate specific antigen (PSA) levels, a researcher here reported.
DALLAS, Dec. 5 -- As low-dose Propecia (finasteride) stimulates hair growth for male pattern baldness, it appears to suppress prostate specific antigen levels, just like its big brother, Proscar, a researcher here reported.
Men who took 1 mg of Propecia daily for hair restoration for 48 weeks reduced serum PSA levels by 40% to 50%, which limited the efficacy of PSA as a screening tool for prostate cancer detection, found urologist Claus Roehrborn, M.D., at the University of Texas Southwestern Medical Center.
The finding from Dr. Roehrborn and his co-author, Anthony V. D'Amico, M.D., of Brigham and Women's Hospital and the Dana-Farber Cancer Institute in Boston, was released online by The Lancet Oncology and will be published in the January edition.
Proscar, which is higher-strength finasteride, is given at 5 mg/day to treat benign prostatic hyperplasia, and, the authors said, it is well known that the 5-mg dose suppresses PSA. As a result, when men who are taking Proscar undergo PSA screening tests, the recommendation is to multiply the value by two in order to compensate for the effect of Proscar.
The authors said that it had been unknown whether 1 mg of Propecia would have a similar effect.
To find out, they enrolled 355 men ages 40 to 60 with male pattern baldness. They were stratified by decade, 40 to 49 and 50 to 60, and randomized in a four-to-one ratio to Propecia (1 mg/day) or placebo. The primary endpoint was effect on serum PSA at 48 weeks.
The median decrease in serum PSA was greatest among men ages 50 to 60 randomized to Propecia -- 50% (95% CI 44%-57%) compared with a median increase of 13% (95% CI 2% to 24%) for same-aged men who were randomized to placebo.
For men ages 40 to 49 the median decrease was 40% (range 34% to 46%) for those in the Propecia arm versus 0% median change for men in the placebo arm (range -14% to 14%).
The authors said the risk of BPH increases with age, which might explain the greater effect observed in the older cohort.
The findings, they said, suggested "that 1 mg/day [Propecia] affects the serum PSA concentration similarly to 5 mg/day [Proscar] over 1 year."
More studies are needed to determine whether this pattern would hold over a larger population or "whether a lower PSA cutoff, on an increase of at least 0.3ng/mL above the established nadir to recommend prostate biopsy in men receiving a 5a-reductase inhibitor will result in increased detection of high grade disease compared with men not receiving a 5a-reductase inhibitor."
But until such studies are completed, the authors recommend that PSA results from men taking Procepia should be doubled in the same way as samples from men on Proscar therapy in order to compensate for the finasteride effect.
The study was funded by Merck & Co., Inc., the maker of finasteride, and the authors disclosed no financial conflicts.