Comparison of Observed Biochemical Recurrence-free Survival in Patients With Low PSA Values Undergoing Radical Prostatectomy and Predictions of Preoperative Nomogram

ObjectivesA preoperative nomogram is an effective tool for assessing the risk of disease progression after radical prostatectomy for localized prostate cancer. To better understand the performance of nomograms for patients with a low prostate-specific antigen (PSA) level, we examined whether patients with a PSA level <2.5 ng/mL had outcomes different than predicted by a validated preoperative nomogram.MethodsA cohort of 6130 patients from 2 referral centers was analyzed. Kaplan-Meier methods were used to estimate the recurrence-free probabilities stratified by PSA group (<2.5 vs ≥2.5 ng/mL). Cox proportional hazards regression analysis was used to evaluate whether the PSA grouping was associated with biochemical recurrence, controlling for preoperative nomogram probability.ResultsOf 6130 patients, 399 (6.5%) had a PSA level <2.5 ng/mL. Patients with a PSA level of ≤0.5 ng/mL had a high rate of nonorgan-confined disease (33% vs 15% for PSA levels of 0.6-2.5 ng/mL). The median follow-up for recurrence-free patients was 2.4 years, and 10 patients with a PSA level of <2.5 ng/mL and 597 patients with a PSA level >2.5 ng/mL developed recurrence (total 607/6130). With adjustment for the preoperative nomogram probability, no significant difference was found in recurrence by PSA grouping (hazard ratio 0.78 for PSA <2.5 vs ≥2.5 ng/mL; 95% confidence interval 0.42-1.48; P = .5).ConclusionsPatients with a low PSA comprise a small proportion of those treated, and most have palpable disease. Patients with especially low PSA values (≤0.5 ng/mL) have a high rate of nonorgan-confined disease. We saw no evidence that patients with low PSA levels have worse outcomes, after the stage and grade were taken into account.