Variation in serum prostate-specific antigen levels in men with prostate cancer managed with active surveillance.
Academic Article
Overview
abstract
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.
