The prognostic value of PSA levels in radiation therapy of patients with carcinoma of the prostate: the UCLA experience 1988-1992.

Abstract

Pretreatment prostate-specific antigen (PSA) levels may be of prognostic significance for patients with prostate cancer. Posttreatment PSA data are more limited. This study was undertaken to examine the prognostic role of pretreatment and posttreatment PSA levels in the radiation treatment of patients with carcinoma of the prostate. One hundred one patients who received primary radiation therapy at UCLA between 1988 and 1992 for clinical stage A to D1 prostate cancer were analyzed. Included were 4 patients with stage A, 77 with stage B, 16 with stage C, and 4 with stage D. All patients had pretherapy and posttherapy PSA values. Patients received definitive radiation therapy with photons (81), neutrons (13), or interstitial implant (7). Correlations were made with other prognostic factors and treatment outcome. Median follow-up was 28 months. At last follow-up, 64% were without evidence of disease, 17% had rising PSA profiles or failure of PSA to normalize (chemical failure), and 19% had local recurrence and/or distant metastases. The 4-year overall survival was 85%, whereas actuarial survival free of chemical or clinical failure was only 32%. Pretreatment PSA levels and posttreatment PSA level normalization at 6 months correlated significantly with disease-free survival. On univariate analysis, pretreatment PSA levels correlated significantly with stage, high versus low Gleason score, and outcome. Posttreatment PSA level normalization at 6 and 12 months correlated with stage, pretreatment PSA level, and outcome, but not with Gleason score. Only PSA level normalization at 6 months and age were independent variables using multivariate analysis. PSA nadir values differed significantly between patients free of disease and those who failed. In our analysis, posttreatment PSA levels were independently predictive of outcome, whereas pretreatment PSA levels, while correlating with other prognostic factors, were not independently predictive. Given the prognostic value of posttreatment PSA levels, it is appropriate that chemical failures be included in outcome analyses, although this will lower disease-free survival.