Prostate-specific antigen as a pretherapy prognostic factor in patients treated with radiation therapy for clinically localized prostate cancer.

Abstract

PURPOSE This study was conducted to determine the value of prostate-specific antigen (PSA) as a pretherapy prognostic factor for localized prostate cancer treated with primary irradiation (RT). PATIENTS AND METHODS Between March 1987 and December 1990, 254 patients with pretherapy PSA determinations were treated for clinical stage A2 to C prostate adenocarcinoma. In conjunction with other prognostic factors, pretherapy PSA was evaluated to determine whether it had independent predictive value for disease outcome. RESULTS Pretherapy PSA was highly and directly correlated with clinical stage, tumor grade, and acid phosphatase level. With a median follow-up duration of 24 months, 241 patients (95%) were fully assessable for disease outcome. In these patients, PSA and tumor grade were the sole independent predictive factors for tumor relapse (ie, clinically determined and/or increasing PSA level). The combination of pretherapy PSA and tumor grade information defined groups of patients with distinctly different outcome. For patients in low- (favorable PSA and tumor grade), intermediate- (favorable PSA or tumor grade), and high- (adverse PSA and tumor grade) risk categories, the actuarial rates of survival free of tumor relapse or increasing PSA level were 94%, 77%, and 42% at 3 years, respectively (P < .0001). CONCLUSION Pretherapy PSA is a strongly independent prognostic factor for disease outcome following primary RT. The combination of adverse pretherapy PSA and unfavorable tumor grade identified a cohort of patients with a high risk of early treatment failure in whom combined modality therapy may be appropriately investigated.