Long-Term Effects of Finasteride vs Placebo on Prostate Cancer Mortality
In a letter to the editor of The New England Journal of Medicine, Goodman et al reported a long-term follow-up of the Prostate Cancer Prevention Trial indicating that finasteride treatment was not associated with an increased risk of death from prostate cancer.
Study Details
As previously reported, in the trial, 18,882 men were randomly assigned to receive finasteride or placebo for 7 years. The primary endpoint was the prevalence of prostate cancer over 7 years. Finasteride reduced the risk of cancer by 24.8%. However, finasteride was associated with greater risk of high-grade cancer (Gleason score 7–10), with this finding leading to recommendations against use of finasteride for prevention.
As noted by the authors, subsequent studies showed that finasteride improved detection of prostate cancer and high-grade prostate cancer by improving the performance characteristics of the prostate-specific antigen (PSA) test, digital rectal examination, and prostate biopsy, potentially explaining bias in the initial study findings. An analysis by the authors in 2013 indicated that overall survival rates in the two study groups were similar. The current analysis assessed rates of prostate cancer–specific survival over 18 years of follow-up.
Prostate Cancer–Specific Mortality
With 296,842 person-years of follow-up and median follow-up of 18.4 years, 3,048 deaths, including 42 due to prostate cancer, occurred in 9,423 men in the finasteride group and 2,979 deaths, including 56 due to prostate cancer, occurred in 9,457 men in the placebo group. These figures yielded an 18-year incidence of death due to prostate cancer of 0.43% vs 0.60%. The hazard ratio for cancer-specific mortality was 0.75 (95% confidence interval = 0.50–1.12). For men dying of prostate cancer in the finasteride vs placebo groups, Gleason scores at diagnosis were ≤ 6 for 7 vs 16, 7 for 5 vs 9, 8 to 10 for 13 vs 11, and unknown for 17 vs 20.
The authors stated, “PSA-detected prostate cancer will likely increase with recommendations to offer screening to men 55 to 65 years of age. Screening may reduce the risk of death from prostate cancer, but often leads to the detection of prostate cancer that will remain asymptomatic during a man’s life. If indolent cancers are treated with surgery or radiation, complications, including impotence and incontinence, are common. If managed with active surveillance, up to 45% of men will ultimately receive treatment; they will also face frequent examination, repeated invasive biopsies, and anxiety. Finasteride is a generic agent that is used to treat lower urinary tract symptoms, prevents complications from these symptoms, and prevents prostate cancer. The early concerns regarding an association between finasteride and an increased risk of high-grade prostate cancer have not been borne out.”
Disclosure: The study was supported by grants from the National Cancer Institute. The study authors’ full disclosures can be found at nejm.org.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
