INTRODUCTION: This retrospective review compares prostate-specific antigen (PSA) doubling time (DT) prior to the initiation of a 5-alpha-reductase inhibitor (pre-5-ARI) to after the PSA nadir (post-nadir) has been reached for patients on active surveillance for favourable-risk prostate cancer.
METHODS: Between 1996 and 2010, a total of 100 men with a history of 5-ARI use were captured from our active surveillance database. Twenty-nine patients had a sufficient number of PSA values to determine both pre-5-ARI and post-nadir DTs. PSADT was calculated using the general linear mixed-model method.
RESULTS: The median follow-up was 69.5 months. The median pre-5-ARI PSADT was 55.8 (range: 6-556.8) months, while the post-nadir value was 25.2 (range: 6-231) months (p = 0.0081). Six patients were reclassified after an average of 67.7 (range: 59-95) months, due to progression in PSADT (n = 2) or Gleason score (n = 4). The median pre-5-ARI and post-nadir DTs for this group were 42.3 (range: 32.4-91.1) and 21.1 (range: 6-44.3) months, respectively.
CONCLUSION: 5-ARIs significantly decreased PSADT compared to prior to their initiation. This effect may be due to preferential suppression of benign tissue following PSA nadir. The resulting PSADT would then represent a more accurate depiction of the true cancer-related DT. If validated with a larger cohort, 5-ARIs may enhance the utility of PSADT as a biomarker of disease progression in active surveillance.
Written by:
Chiang AS1, Loblaw DA1, Jethava V1, Sethukavalan P1, Zhang L2, Vesprini D1, Mamedov A3, Nam R4, Klotz L4 Are you the author?
1Department of Radiation Oncology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON; 2Department of Biostatistics, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON; 3Department of Clinical Trials and Epidemiology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON; 4Division of Urology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON.
Reference: Can Urol Assoc J. 2013 Nov;7(11-12):450-3
doi: 10.5489/cuaj.262
PubMed Abstract
PMID: 24381668
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