Early toxicity of moderate hypofractionated volumetric modulated Arc radiotherapy for localized prostate cancer

Background: Based on the radiation biology model of prostate cancer, hypofractionated radiotherapy can improve the treatment outcomes without increasing toxicity. Although hypofractionated radiotherapy is implemented over a short period of time, it is more convenient and cheaper compared with conventional fractionated treatment. The aim of this study was to investigate the early toxicity of moderate hypofractionated schedules with volumetric modulate arc radiotherapy (VMAT) for localized prostate. Materials and Methods: Between 2014-2017, 41 patients were treated using the volumetric modulated arc radiotherapy (VMAT) technique with image guided radiotherapy. The target volume for low risk patient (2.4%) was the prostate alone, and that for intermediate (43.9%) and high risk patients (53.7%) was prostate and two thirds of the seminal vesicles. A prescription dose of 70 Gy in 2.5 Gy daily for 28 treatment was used. Radiotherapy-related toxicity was scored according to the Common Terminology Criteria for Adverse Events 4.0 criteria. Results: Early genitourinary (GU) toxicity was recorded for grades 0, 1, 2 and 3 in 7 (17.1%), 25 (61.0%), 9 (21.9%) and 0 patients, respectively. Most common GU toxicities were urinary frequency and urgency. Early gastrointestinal (GI) toxicity was observed for grade 0, 1 and 2 in 35 (85.4%), 6 (14.6%) and 0 patients, respectively. Most common GI toxicity was rectal discomfort but interventional therapy was not indicated. Conclusion: The moderate hypofractionated VMAT radiation therapy with precise dose delivery technique appeared safe with low early toxicity. Longer follow up is needed to assess late toxicity and tumor control probability.