Men aged 55 and over with a normal digital rectal examination and PSA less than or equal to 3.0 ng/mL at baseline taking Finasteride 5 mg/day ( 5 times the dose of Propecia ) in the 7-year Prostate Cancer Prevention Trial ( PCPT ) had an increased risk of Gleason score 8-10 prostate cancer ( Finasteride 1.8% vs placebo 1.1% ).
Similar results were observed in a 4-year placebo-controlled clinical trial with another 5-alpha reductase inhibitor ( Dutasteride, Avodart ) ( 1% Dutasteride vs 0.5% placebo ).
5-alpha-reductase inhibitors may increase the risk of development of high-grade prostate cancer. Whether the effect of 5-alpha reductase inhibitors to reduce prostate volume, or study-related factors, impacted the results of these studies has not been established.

During the 4- to 6-year placebo- and comparator-controlled Medical Therapy of Prostatic Symptoms ( MTOPS ) study that enrolled 3,047 men, there were 4 cases of breast cancer in men treated with Proscar but no cases in men not treated with Proscar.
During the 4-year placebo-controlled study that enrolled 3,040 men, there were 2 cases of breast cancer in placebo-treated men but no cases in men treated with Proscar.
During the 7-year placebo-controlled Prostate Cancer Prevention Trial ( PCPT ) that enrolled 18,882 men, there was 1 case of breast cancer in men treated with Proscar, and 1 case of breast cancer in men treated with placebo.
The relationship between long-term use of Finasteride and male breast neoplasia is currently unknown.

The PCPT trial was a 7-year randomized, double-blind, placebo-controlled trial that enrolled 18,882 healthy men greater than or equal to 55 years of age with a normal digital rectal examination and a PSA less than or equal to 3.0 ng/mL. Men received either Proscar ( Finasteride 5 mg ) or placebo daily. Patients were evaluated annually with PSA and digital rectal exams. Biopsies were performed for elevated PSA, an abnormal digital rectal exam, or the end of study. The incidence of Gleason score 8-10 prostate cancer was higher in men treated with Finasteride ( 1.8% ) than in those treated with placebo ( 1.1% ). In a 4-year placebo-controlled clinical trial with another 5-alpha-reductase inhibitor ( Dutasteride ), similar results for Gleason score 8-10 prostate cancer were observed ( 1% Dutasteride vs 0.5% placebo ).

The clinical significance of these findings with respect to use of Propecia by men is unknown.

No clinical benefit has been demonstrated in patients with prostate cancer treated with Proscar. Proscar is not approved to reduce the risk of developing prostate cancer. ( Xagena )

Source: FDA, 2011

XagenaMedicine2011