Early biochemical predictors of survival in intermediate and high-risk prostate cancer treated with radiation and androgen deprivation therapy.

Abstract

To identify early biochemical predictors of survival in intermediate- and high-risk prostate cancer patients with a pre-treatment PSA <20 ng/mL following definitive radiation therapy (RT) and androgen deprivation therapy (ADT). A single-institution review of 2566 intermediate and high-risk prostate cancer patients treated with definitive RT and neoadjuvant and concurrent ADT from 1990 to 2012 was performed. The first prostate-specific antigen (PSA) value within three months of ADT initiation (post-ADT PSA) and the first PSA within three months after RT completion (post-RT PSA) were recorded. 1275 had baseline PSA <20 ng/mL and either post-ADT or post-RT PSA available. Median follow-up was 7.6 years. The relationship between post-treatment PSA kinetics and biochemical relapse (BR), distant metastasis (DM), prostate cancer specific death (PCSD) and overall survival (OS) was modeled using Cox regression univariate and multivariate analysis (MVA). MVA demonstrated a strong association between a post-RT PSA ≥0.09 ng/mL and a significantly higher risk of BR (HR: 1.93; 95% CI: 1.45-2.57; p < 0.001), DM (HR: 2.97; 95% CI: 2.01-4.39; p < 0.001), PCSD (HR: 2.99; 95% CI: 1.73-5.15; p < 0.001) and OS (HR: 1.49; 95% CI: 1.18-1.86; p < 0.001). Post-RT PSA reduction of ≥95% relative to the baseline PSA was associated with a significantly lower risk of BR (MVA HR: 0.58; 95% CI: 0.41-0.83; p = 0.003) and DM (MVA HR: 0.47; 95% CI: 0.30-0.76; p = 0.002). A PSA value ≥0.09 ng/mL early after RT completion is associated with significantly worse prognosis across all clinical outcomes, and an early PSA reduction of ≥95% is associated with reduced risk of BR and DM. These findings may identify patients who require early aggressive systemic management for high-risk disease.