Recurrence‐free survival rates after external‐beam radiotherapy for patients with clinical T1–T3 prostate carcinoma in the prostate‐specific antigen era

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. Cancer 2004. © 2004 American Cancer Society.