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

Abstract

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. 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. 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. 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.