Treatment outcomes of three-dimensional conformal radiotherapy for localized prostate carcinoma - A large community-based experience

BACKGROUND. The current study documented the implementation of three-dimensional conformal radiotherapy and assessed the tumor control and toxicity of such treatment in a large, multisite community practice. METHODS. The authors retrospectively reviewed their first 222 consecutive patients with clinically localized (NO) prostate carcinoma treated with a 6-field conformal technique from October 1993 through March 2000. Standardized target definitions, dose planning constraints, and gantry angles were utilized to develop the treatment plan. Patients were categorized by low, intermediate, and high risk. Low risk was defined as T1a-T2a disease, a Gleason score < 7, and prostate-specific antigen (PSA) level less than or equal to 10.0 ng/mL (n = 47 [21%]). Intermediate risk was defined as T2b disease, a Gleason score > 6, or PSA level > 10.01 ng/mL (n = 60 [27%]). High risk was defined as 2 of the above risk factors or as T3 disease, a Gleason score > 7, or a PSA level > 20 (n = 115 [52%]). Biochemical disease recurrence was defined in accordance with the American Society for Therapeutic Radiology and Oncology definition. Urinary and bowel toxicity were graded using the Radiation Therapy Oncology Group morbidity scoring system. RESULTS. The median follow-up after radiotherapy for surviving patients was 47 months (range, 0-99 months). The 2 and 5-year actuarial biochemical control rates for all patients were 84% and 78%, respectively. Using logistic regression analysis, lower dose (< 75.6 gray [Gy] vs. 75.6 Gy; P = 0.006), higher risk group (P = 0.033), higher stage (P = 0.045), and higher PSA level (P = 0.001) were significantly associated with biochemical disease recurrence. Toxicity was not significantly correlated with a higher radiotherapy dose. CONCLUSIONS. Dose escalation to 75.6 Gy using a 6-field conformal technique was feasible in the authors' community practice and resulted in acceptable toxicity and early biochemical outcomes. (C) 2004 American Cancer Society.