We will presumably be at least a little wiser about this issue when data from the REDEEM trial are presented at the Genitourinary Cancers Symposium in Orlando on Thursday; however, data from Canada already suggest that 5α-reductase inhibitors (5-ARIs) affect progression of low-risk forms of prostate cancer.
Finelli et al. conducted a single-institution, retrospective analysis of data from patients with prostate cancer being managed on an active surveillance protocol who were or were not also being treated with a 5-ARI (either finasteride or dutasteride). They carefully assessed available data on pathologic progression of disease (defined as a Gleason score > 6), maximum biopsy core involvement > 50%, or the presence of more than three positive cores at the time of follow-up prostate biopsies.
Here are the top-line results of their study:
- 288 men on active surveillance met the inclusion criteria for the study.
- Average (median) follow-up was 38.5 months.
- 93/288 men (32 percent) showed evidence of pathologic progression.
- 96/288 men (33 percent) abandoned active surveillance.
- Men taking a 5-ARI had a lower rate of pathologic progression than men not taking a 5-ARI (18.6 vs 36.7 percent; p = 0.004).
- Men taking a 5-ARIwere also less likely to abandon active surveillance (20.0 vs 37.6 percent; p = 0.006).
- Lack of 5-ARI use was strongly associated with pathologic progression (hazard ratio = 2.91)
Obviously this type of single-institution, retrospective data analysis needs to be interpreted with caution, and follow-up in this study only averaged a little more than 3 years, but there is clearly an effect of 5-ARIs on prostate cancer that appears to delay the need for interventional therapy in men with low-risk disease. Understanding the clinical significance of this effect will need follow-up of more like 10 to 15 years.