Impact of Dutasteride on PSA Kinetics and Time to Progression in Men with PSA-only Recurrent Prostate Cancer

Abstract

Background: AVODART After Radical Therapy For Prostate Cancer Study (ARTS) reported dutasteride reduced PSA Doubling (PSADT) at two years by 66% and disease progression by 59%. The durability of the cancer control is unknown. Objective: Explore the impact of dutasteride on PSADT and time to progression in men with PSA-only recurrent disease. Design, Setting and Participants: Retrospective examination of the impact of dutasteride on PSA kinetics and time to progression with PSA-only recurrent prostate cancer. Intervention: Dutasteride daily. Outcome, measurement and statistical analysis: Change in PSA over time was determined by linear regression of natural log of PSA versus time. The slope of that curve was used as a measure of exponential PSA progression. Impact of dutasteride on slope was analyzed using Wilcoxon signed-rank two-sided test. Time to progression was analyzed using Kaplan-Meier, univariant and multivariant Cox regression. Results and limitation: Compared to men with BPH, patients showed little change in PSA during the first 3 months. Thereafter, the PSA resumed an exponential increase. PSADT was 10.3 months pre dutasteride and 24.8 months post dutasteride. Multivariant analysis showed a strong correlation between post dutasteride PSA kinetics and time to progression, with close to 50% relapse free at 10 years. Post-dutasteride, patients with PSADT >9 months had significantly better survival. Conclusion: Dutasteride slows PSADT in PSA-only recurrent prostate cancer. This decline correlated with time to disease progression with close to 50% progression free at 10 years. Patient summary: Men with PSA-only recurrent prostate cancer on dutasteride experience a significant drop in the rate at which the PSA increases. If the PSA does not double between months 3-12, they are likely to remain free of metastases for many years.