PCPT Trial Explained: Design, Results and Long-Term Follow-Up
Medically reviewed by [Reviewer Name, MD, Urology/Oncology] | Last reviewed: August 2026 | Editorial policy
The Prostate Cancer Prevention Trial (PCPT; Thompson et al., 2003; N Engl J Med) found that finasteride 5 mg reduced prostate cancer prevalence by 24.8% over 7 years. But also found a higher proportion of high-grade (Gleason 7-10) cancers in the finasteride group. This finding generated substantial controversy and led to FDA safety communications. Subsequent analyses have provided important context.
Study Design
| Parameter | Details |
|---|---|
| Design | Double-blind, placebo-controlled RCT |
| Population | Men ≥55 years, PSA ≤3 ng/mL, normal digital rectal exam; n=18,882 |
| Treatment | Finasteride 5 mg/day vs. placebo for 7 years; biopsy at study end |
| Endpoint | Prostate cancer prevalence at biopsy (end of study) |
Key Results and the High-Grade Cancer Controversy
| Outcome | Finasteride | Placebo |
|---|---|---|
| Overall prostate cancer prevalence | 18.4% | 24.4% |
| Relative risk reduction | 24.8% | N/A |
| High-grade cancer (Gleason 7-10) prevalence | 6.4% | 5.1% |
The Detection Bias Explanation
The prevailing scientific explanation for the higher high-grade cancer rate is detection bias, not causation. Finasteride shrinks prostate volume by 20-30%; a smaller prostate means a biopsy needle samples proportionally more of the gland, making it more likely to detect any cancer that is present, including high-grade cancer. A later analysis (Lucia et al., 2007) concluded that the smaller prostate volume in the finasteride group may have contributed to the finding, while stating that induction of high-grade cancer cannot be excluded. The Thompson et al. 2013 NEJM follow-up, with up to 18 years of data, found no significant difference in overall survival (15-year survival 78.0% vs. 78.2%) or in survival after a prostate cancer diagnosis between the finasteride and placebo groups.
Major urology guidelines (AUA, EAU) do not conclude that finasteride causes high-grade prostate cancer. The FDA added a label warning noting the observation.
Sources
- Thompson IM, et al. “The influence of finasteride on the development of prostate cancer.” N Engl J Med. 2003;349(3):215-224.
- Thompson IM, et al. “Long-term survival of participants in the Prostate Cancer Prevention Trial.” N Engl J Med. 2013;369(7):603-610.