Prognostic significance of undetectable ultrasensitive prostate-specific antigen nadir after radical prostatectomy.

OBJECTIVES To investigate the prognostic significance of undetectable ultrasensitive prostate-specific antigen (PSA) nadir in patients who received radical prostatectomy (RP) for prostate cancer. METHODS We reviewed records of 384 patients who received RP for prostate cancer and were followed for at least 2 years with ultrasensitive PSA testing. Undetectable ultrasensitive PSA level was defined as <0.001 ng/mL. Subjects were categorized according to PSA nadirs: <0.001 ng/mL (group 1), 0.001 ng/mL ≤ and < 0.02 ng/mL (group 2), 0.02 ng/mL ≤ and < 0.05 ng/mL (group 3), or ≥0.05 ng/mL (group 4). Multivariate analysis was performed to identify independent predictors of biochemical recurrence-free survival. A receiver operator characteristics (ROC) curve was used to assess performances of multivariate model in predicting biochemical recurrence. RESULTS Overall, 206 (53.6%) patients showed undetectable ultrasensitive PSA nadir. Subjects of groups 1, 2, 3, and 4 demonstrated significant differences in biochemical recurrence-free survivals (log rank P <.001). In multivariate analysis, undetectable ultrasensitive PSA nadir (P <.001) was observed to be an independent predictor of biochemical recurrence-free survival along with preoperative PSA level (P = .030), pathologic stage (P = .014), and pathologic Gleason score (P = .042). Area under the ROC curve demonstrating predictive performances of the multivariate model, which included ultrasensitive PSA nadir, was significantly larger than that of the model without it (P <.001). CONCLUSIONS Our results demonstrated that undetectable ultrasensitive PSA nadir is a useful predictor of biochemical recurrence-free survival among contemporary patients who received RP for prostate cancer.