Acute and late genitourinary toxicity of conformal radiotherapy for prostate cancer

Purpose. The aim of this study was to identify predictive factors for genitourinary (GU) toxicity in prostate cancer patients who underwent conformal radiotherapy (CRT). Materials and methods. In this study we analyzed 154 cases of T1-3N0M0 prostate adenocarcinoma and evaluated the occurrence rate of acute and late GU toxicity and the duration of acute toxicity according to clinical parameters: age, transurethral resection of the prostate prior to CRT, hormone therapy, CRT dose, length of planning target volume (PTV). Results. Altogether, 41% of the patients developed grade 2 or higher acute GU toxicity. Longer PTV was significantly associated with a higher incidence of acute GU toxicity (>7cm, 53%; ≤7cm, 31%; P = 0.003), and hormone therapy prolonged the duration of the toxicity (P = 0.007). Grade 1 or higher late GU toxicity developed in 23% of the patients, and the 2-year late GU toxicity-free survival rate was 79%. Acute GU toxicity was significantly associated with the late GU toxicity-free survival rate (grade 0-1, 88.7%; grade 2-4, 73.2%; P = 0.0007). Conclusion. The length of PTV and hormone therapy were predictive factors for acute GU toxicity. Furthermore, acute GU toxicity was the most important predictive factor for late GU toxicity. © 2006 Japan Radiological Society.