Long-Term Outcome With Finasteride Using Medicare Claims Linked to the Prostate Cancer Prevention Trial


Key Points

  • The original finasteride group maintained significantly reduced risk for prostate cancer over 16 years.
  • Risk reduction was significant during the first 7.5 years, with no significant increase in risk observed thereafter. 

In a study reported in the Journal of the National Cancer Institute, Unger et al linked data from the Prostate Cancer Prevention Trial (PCPT) with Medicare claims and found that finasteride treatment was associated with a maintained reduction in prostate cancer risk after discontinuation of the study treatment.

Study Details

The PCPT study showed that 7 years of finasteride treatment reduced prostate cancer risk by 25% in men aged ≥ 55 years. The current study used linked PCPT records and Medicare claims for 9,423 patients in the finasteride group and 9,457 in the placebo group to determine if finasteride treatment remained protective beyond the 7-year treatment period. A Medicare-defined prostate cancer diagnosis algorithm was defined using diagnosis and procedure codes.

Long-Term Outcomes

Median follow-up using the linked database was 16 years. Overall, the finasteride group maintained a significantly reduced risk of prostate cancer (hazard ratio [HR] = 0.79, P < .001) over 16 years of follow-up. The benefit of finasteride vs placebo in risk reduction was greatest in the first 7.5 years (HR = 0.71, P < .001), consistent with the original study findings. After 7.5 years, there was no significantly increased risk of prostate cancer among the finasteride recipients (HR = 1.10, P = .18).

The investigators concluded, “Finasteride provides a substantial reduction in [prostate cancer] through 16 years of follow-up. There was no strong evidence that the benefit of finasteride diminished after the end-of-study follow-up. Utilizing Medicare claims to augment PCPT follow-up illustrates how the novel use of secondary data sources can enhance the ability to detect long-term outcomes from prospective studies.”

The study was supported by the National Cancer Institute.

Joseph M. Unger, PhD, of the SWOG Statistical Center, Fred Hutchinson Cancer Research Center, is the corresponding author for the Journal of the National Cancer Institute article. 

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®.