Timing of Prostate-specific Antigen Nadir After Radical Prostatectomy and Risk of Biochemical Recurrence

Objective To evaluate the association between the prostate-specific antigen (PSA) nadir level and the time to nadir (TTN) with biochemical recurrence (BCR) risk after radical prostatectomy (RP) in the Shared Equal-Access Research Cancer Hospital (SEARCH) database. Materials and Methods This is a retrospective analysis of 1939 men from the SEARCH database treated with RP between 1998 and 2015 with available ultrasensitive PSA nadir within 1-6 months after RP. Uni- and multivariable analyses of PSA nadir and TTN with time from nadir to BCR were performed with Cox models (adjusted for demographics, tumor features, and preoperative PSA). Results Among men with an undetectable PSA nadir, the TTN was unrelated to BCR (1.0-2.9 vs 3-6 months: hazard ratio [HR] 0.86, P =.46). Regardless of TTN, men with detectable nadir had an increased risk of BCR (TTN of 3-6 months: HR 1.81, P =.024; TTN of 1.0-2.99 months: HR 3.75, P <.001 vs undetectable nadir and TTN of 3-6 months). Among men with a detectable PSA at 1-3 months, 53% had a lower PSA level during follow-up 3-6 months after RP, which was undetectable in 32% and lower but still detectable in 21%. Conclusion In the post-RP setting, men with both a detectable nadir and a shorter TTN had an increased risk of BCR. Intriguingly, about half of the men with a detectable PSA in the first 3 months after RP had a lower PSA level during follow-up between 3 and 6 months after RP. If confirmed in future studies, this has important implications for patients considering adjuvant therapy based on postoperative PSA values in the first 3 months after RP.