LOCALIZED PROSTATE-CANCER TREATED BY EXTERNAL-BEAM RADIOTHERAPY ALONE - SERUM PROSTATE-SPECIFIC ANTIGEN-DRIVEN OUTCOME ANALYSIS

Purpose: To determine the 5-year rate of survival with no evidence of disease (NED) using strict biochemical criteria in men with prostate cancer treated by external-beam radiotherapy alone and to examine possible clinical and treatment factors that predict the likelihood of NED survival. Materials and Methods: Five hundred men with clinically localized prostate cancer consecutively treated with external-beam radiotherapy alone with no prior, concomitant, or adjuvant endocrine therapy were identified. All patients had serial serum prostate-specific antigen (PSA) values determined after treatment and 451 patients had pretreatment PSA values determined. The median follow-up duration is 20 months (range, 2 to 72; mean, 36). Results: The 5-year rate of overall survival in this group of patients was 80%. The 5-year rate of survival without clinical evidence of disease (cNED) was 72%. The 5-year rate of survival without evidence of clinical, radiographic, or biochemical relapse (bNED) was 51%. Multivariate analysis demonstrated that a pretreatment serum PSA level less than or equal to 15 ng/mL was the most important predictor of bNED survival (P<.0001). Patients with early-stage (T1,T2a/b) tumors and a pretreatment serum PSA less than 15 ng/mL had a 9-year rate of bNED survival of 86%. The rate of bNED survival for patients with a pretreatment PSA level greater than 15 ng/mL was 38% at 3 years. Conclusion: Pretreatment serum PSA level is the most important predictor of treatment outcome in this group of patients treated with definitive radiotherapy alone. External-beam radiation alone can produce acceptable early rates of bNED survival in patients with clinically organ-confined tumors and a pretreatment PSA level less than or equal to 15 ng/mL. To produce acceptable results in those patients with pretreatment PSA levels more than 15 ng/mL, effective adjuvant treatments in addition to aggressive local treatments are necessary.