HYPOFRACTIONATED INTENSITY-MODULATED ARC THERAPY FOR LYMPH NODE METASTASIZED PROSTATE CANCER

Purpose: To determine the planning results and acute toxicity after hypofractionated intensity-modulated are radiotherapy and androgen deprivation for lymph node metastasized (Stage N1) prostate cancer. Methods and Materials: A total of 31 patients with Stage T1-T4N1M0 prostate cancer were treated with intensity-modulated arc radiotherapy and 3 years of androgen deprivation as primary treatment. The clinical target volume (CTVp) was the prostate and seminal vesicles. Elective lymph node areas ((e)) were delineated and expanded by 2 mm to create the CTVe. The planning target volumes (PTVp and PTVe) were created using a three-dimensional expansion of the CTVp and CTVe, respectively, of 7 mm. A median dose of 69.3 Gy and 50 Gy was prescribed to the PTVp and PTVe respectively, to be delivered in 25 fractions. Upper and lower gastrointestinal toxicity was scored using the Radiation Therapy Oncology Group toxicity and radiotherapy-induced lower intestinal toxicity scoring system. Genitourinary toxicity was scored using a combined Radiation Therapy Oncology Group, LENT-SOMA (late effects normal tissue-subjective, objective, management, analytic), and Common Toxicity Criteria toxicity scoring system. Results: The median follow-up time was 3 months. The mean prescription dose to the CTVp and PTVp was 70.4 Gy and 68.6 Gy, respectively. The minimal dose to the CTVe and PTVe was 49.0 Gy and 47.0 Gy, respectively. No acute Grade 2 or greater gastrointestinal toxicity occurred. Fourteen patients developed acute Grade 2 lower gastrointestinal toxicity. Acute Grade 3 and 2 genitourinary toxicity developed in 2 and 14 patients, respectively. Conclusion: The results of our study have shown that hypofractionated intensity-modulated arc radiotherapy as primary therapy for NI prostate cancer is feasible with low toxicity. (C) 2009 Elsevier Inc.