Recurrence-Free Survival Rates after External-Beam Radiotherapy for Patients with Clinical T1-T3 Prostate Carcinoma in the Prostate-Specific Antigen Era: What Should We Expect?

Abstract

BACKGROUND. The objective of the current study was to report biochemical recurrence-free survival (bRFS) rates among men with T1-T3 prostate carcinoma who were treated with external-beam radiotherapy (RT) at the Cleveland Clinic Foundation (Cleveland, OH). METHODS. In total, 1352 patients were identified between 1987 and 2000 with a minimum follow-up of 1 year (median follow-up, 55 months; range, 12-189 months). The median radiation dose was 74.0 grays (Gy) (range, 63.0-83.0 Gy). The median radiation doses for patients who received < 68.0 Gy (n = 201), 68.0-72.0 Gy (n = 373), and ≥ 72.0 Gy (n = 778) were 66.6 Gy, 70.0 Gy, and 78.0 Gy, respectively. The RT techniques used were standard RT in 41% of patients, 3-dimensional conformal RT in 34% of patients, and intensity-modulated RT in 25% of patients. Androgen-deprivation (AD) therapy lasting ≤ 6 months was administered to 34% of patients. RESULTS. The 5-year and 7-year bRFS rates were 63% and 59%, respectively. On multivariate analysis, T classification (P < 0.001), pretreatment prostate-specific antigen level (P < 0.001), biopsy Gleason score (P = 0.001), radiation dose (P < 0.001), and year of therapy (P < 0.001) were independent predictors of biochemical failure. Age, race, AD therapy, and RT technique did not predict for biochemical failure. For patients with low-risk tumors, the 5-year bRFS rates for those who received RT doses of ≤ 68.0 Gy, 68.0-72.0 Gy, and ≥ 72.0 Gy were 52%, 82%, and 93%, respectively (P < 0.001); for patients with intermediate-risk tumors, the respective 5-year bRFS rates were 27%, 51%, and 83% (P < 0.001); and for patients with high-risk tumors, the respective 5-year bRFS rates were 21%, 29%, and 71%, respectively (P < 0.001). CONCLUSIONS. The most significant therapeutic factor affecting bRFS rates after RT was radiation dose, rather than AD therapy use or radiation technique. © 2004 American Cancer Society.