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Updated: Jun 22, 2026
An Orthotopic Murine Model of Human Prostate Cancer Metastasis
Published on: September 19, 2013
The influence of finasteride on the development of prostate cancer
Ian M Thompson1, Phyllis J Goodman, Catherine M Tangen
1University of Texas Health Science Center, San Antonio, USA.
Background:
Androgens are involved in the development of prostate cancer. Finasteride, an inhibitor of 5alpha-reductase, inhibits the conversion of testosterone to dihydrotestosterone, the primary androgen in the prostate, and may reduce the risk of prostate cancer.
Methods:
In the Prostate Cancer Prevention Trial, we randomly assigned 18,882 men 55 years of age or older with a normal digital rectal examination and a prostate-specific antigen (PSA) level of 3.0 ng per milliliter or lower to treatment with finasteride (5 mg per day) or placebo for seven years. Prostate biopsy was recommended if the annual PSA level, adjusted for the effect of finasteride, exceeded 4.0 ng per milliliter or if the digital rectal examination was abnormal. It was anticipated that 60 percent of participants would have prostate cancer diagnosed during the study or would undergo biopsy at the end of the study. The primary end point was the prevalence of prostate cancer during the seven years of the study.
Results:
Prostate cancer was detected in 803 of the 4368 men in the finasteride group who had data for the final analysis (18.4 percent) and 1147 of the 4692 men in the placebo group who had such data (24.4 percent), for a 24.8 percent reduction in prevalence over the seven-year period (95 percent confidence interval, 18.6 to 30.6 percent; P<0.001). Tumors of Gleason grade 7, 8, 9, or 10 were more common in the finasteride group (280 of 757 tumors [37.0 percent], or 6.4 percent of the 4368 men included in the final analysis) than in the placebo group (237 of 1068 tumors [22.2 percent], P<0.001 for the comparison between groups; or 5.1 percent of the 4692 men included in the final analysis, P=0.005 for the comparison between groups). Sexual side effects were more common in finasteride-treated men, whereas urinary symptoms were more common in men receiving placebo.
Conclusions:
Finasteride prevents or delays the appearance of prostate cancer, but this possible benefit and a reduced risk of urinary problems must be weighed against sexual side effects and the increased risk of high-grade prostate cancer.
Insights
Finasteride significantly reduced prostate cancer prevalence over seven years. However, it was associated with an increased risk of high-grade tumors and sexual side effects, requiring careful consideration of benefits versus risks.
Area of Science:
- Oncology
- Urology
- Pharmacology
Background:
- Androgens play a role in prostate cancer development.
- Finasteride inhibits 5alpha-reductase, reducing dihydrotestosterone (DHT), the primary prostate androgen.
- This mechanism suggests finasteride may lower prostate cancer risk.
Purpose of the Study:
- To evaluate the efficacy of finasteride in preventing prostate cancer.
- To assess the impact of finasteride on prostate cancer prevalence over a seven-year period.
Main Methods:
- The Prostate Cancer Prevention Trial enrolled 18,882 men aged 55+ with low PSA and normal DRE.
- Participants received either finasteride (5 mg/day) or placebo for seven years.
- Biopsies were triggered by elevated PSA levels or abnormal DRE findings.
Main Results:
- Finasteride reduced prostate cancer prevalence by 24.8% over seven years (18.4% vs. 24.4%).
- High-grade prostate cancers (Gleason 7-10) were more frequent in the finasteride group (6.4% vs. 5.1%).
- Sexual side effects were higher with finasteride; urinary symptoms were more common with placebo.
Conclusions:
- Finasteride effectively prevents or delays prostate cancer onset.
- The benefits of reduced cancer prevalence and urinary issues must be balanced against increased risks of high-grade cancer and sexual side effects.
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