Variation in serum prostate-specific antigen levels in men with prostate cancer managed with active surveillance.

Objective To describe fluctuations in prostate-specific antigen (PSA) levels in men managed with active surveillance (AS) to determine if a single PSA increase is a consistent measure to use to trigger intervention. Patients and Methods We evaluated data on 541 patients undergoing AS between 1995 and 2011. PSA variation was described by studying the Kaplan–Meier probability of patients’ PSA levels reaching 4 or 7 ng/mL, falling below those thresholds, and then rising to those thresholds again. We also examined PSA variation by calculating the Kaplan–Meier probability of a PSA change followed by an equal or greater change in the opposite direction. Results We analysed data on 541 patients undergoing AS with a median (interquartile range [IQR]) of 8 (6–12) PSA measurements and undergoing AS for a median (IQR) of 4 (2–6) years. The 5-year estimate of the probability of reaching a threshold PSA of 7 ng/mL was 40% (95% confidence interval [CI] 35–46%) and the 5-year estimate of subsequently falling below this threshold was 90% (95% CI 82–95%). The 5-year estimate of a PSA direction change was 95% (95% CI 93–97%) overall and 56% (95% CI 51–61%) for PSA direction changes of ≥1 ng/mL. Conclusions We observed a high probability of variability in PSA levels for patients on AS. The probability of changes in PSA, defined by an increase to the specified thresholds or a rise >1 ng/mL within 6 months and subsequent decrease of equal or greater value on a subsequent measurement, increases over time; therefore, a single change in PSA level is not a reliable endpoint for patients on AS.