Finasteride Does Not Affect Survival Rates in Prostate Cancer

September 2013, Vol 4, No 7

Widespread adoption of prostate- specific antigen (PSA) screening has been associated with a 44% reduction in prostate cancer mortality. Although early detection of prostate cancer with PSA testing may lead to reduced mortality, it also leads to significant overdetection of cancer. Another approach that complements early detection is prostate cancer prevention. The use of finasteride, a 5-alpha reductase inhibitor, was evaluated in the Prostate Cancer Prevention Trial (PCPT).

The investigators randomized nearly 19,000 healthy, cancer-free men aged ≥55 years to daily finasteride or to placebo for 7 years. Data published in 2003 showed that the drug was associated with a 24.8% reduction in the risk for prostate cancer. Participants in the finasteride arm, however, had a 26.9% increased incidence of high-grade prostate cancer. With up to 18 years of follow-up, ending October 31, 2011, a new study analyzed the survival rates among all participants in the PCPT and among those with prostate cancer (Thompson IM Jr, et al. N Engl J Med. 2013;369:603-610).

PCPT was a randomized, placebo-controlled study that ran from 1993 to 2003 and included 18,880 men. The updated results showed that prostate cancer was diagnosed in 10.5% of men in the finasteride group and in 14.9% of men in the placebo group (relative risk [RR] in the finasteride group, 0.70; 95% confidence interval [CI], 0.65-0.76; P <.001). The results also showed that the finasteride arm had a 3.5% incidence of high-grade prostate cancer compared with 3.0% in the placebo arm (RR, 1.17%; 95% CI, 1.00-1.37; P = .05). Of the 5034 deaths reported, 2538 were in the finasteride-treated group and 2406 were in the group receiving placebo, for 15-year survival rates of 78.0% and 78.2%, respectively. The unadjusted hazard ratio for death in the finasteride arm was 1.02 (95% CI, 0.97-1.08; P = .46). When stratified by cancer grade, the 10-year survival rates were 83.0% in the finasteride-treated group and 80.9% in the group receiving placebo for low-grade prostate cancer and 73.0% and 73.6%, respectively, for those with high-grade prostate cancer.

These results show that finasteride reduced the risk of prostate cancer by nearly 33%. Although high-grade prostate cancer was more common in the finasteride group than in the placebo group, 18 years of follow-up showed no significant difference between the 2 groups in overall survival rates or survival after a diagnosis of prostate cancer.

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