The Impact of the Percent of Residual Prostate-Specific Antigen on Metastasis-Free Survival in Patients with Persistent Prostate-Specific Antigen after Radical Prostatectomy

PURPOSE: Persistent levels of prostate-specific antigen (PSA) is a poor prognostic factor for recurrence after radical prostatectomy (RP). We investigated the impact of the percentage of residual PSA (%rPSA) [(post-/preoperative PSA)×100], representing a biochemical residual tumor, and the first postoperative PSA (fPSA) level on metastasis-free survival (MFS) in men with persistent levels of PSA after RP. MATERIALS AND METHODS: We retrospectively identified male patients within a single tertiary referral hospital database who harbored persistent (≥0.1 ng/mL) vs. undetectable (<0.1 ng/mL) PSA levels 4 to 8 weeks after RP. Kaplan–Meier analyses and Cox regression models were used to test the effect of persistent PSA levels, the fPSA level, and %rPSA on MFS. RESULTS: Of 1,205 patients, 178 patients with persistent PSA levels were enrolled. Seven-year MFS rates were 60.5% vs. 84.3% (p<0.001) for patients with a %rPSA ≥6% and <6%, respectively. Multivariable Cox regression models of the overall cohort revealed that persistent PSA levels (hazard ratio [HR], 3.94; p=0.010), extracapsular extension (HR, 4.17; 95% confidence interval [CI], 1.06–16.41; p=0.041), and pathological Gleason grade group (pGGG) (HR, 3.69; 95% CI, 1.32–10.27; p=0.013) were independent predictors of metastasis. Multivariable Cox regression models in men with persistent PSA levels revealed that the %rPSA (HR, 8.92; 95% CI, 1.74–45.71; p=0.009) and pGGG 4–5 (HR, 4.13; 95% CI, 1.22–13.96; p=0.022) were independent predictors of distant metastasis, but not the fPSA level after surgery. CONCLUSIONS: Persistent levels of PSA were associated with worse MFS after RP. In men with persistent PSA levels after RP, the %rPSA is a valuable predictor of MFS unlike the fPSA level.