P3-13-1 - Volumetric Modulated Arc Therapy(Vmat) for the Treatment of Localized Prostate Cancer

Abstract

Objective: To report the initial biochemical outcomes and acute and late toxicities in patients with clinically localized prostate cancer treated with volumetric modulated arc therapy (VMAT).Methods: Between November 2007 and September 2011, 200 patients with clinically localized prostate cancer were treated with VMAT. A total of 181 patients received 76 Gy, and 17 patients received 72 Gy. Acute and late toxicities were scored according to the CTCAE grading scales. PSA relapse was defined according to the Phoenix definition.Results: The median follow-up duration was 50 months. Two patients (1%) developed acute Grade 2 or higher GI toxicity. Thirty-nine patients (19%) developed acute Grade 2 GU symptoms, and no patient experienced Grade 3 GU toxicity. Six patients (3%) developed late Grade 2 rectal bleeding. Two patients (1%) experienced Grade 3 rectal toxicity. The 5-year actuarial likelihood of late Grade 2 or higher rectal bleeding was 3.4%.Twenty patients (10%) experienced late Grade 2 or worse GU toxicities. The 5-year actuarial likelihood of late Grade 2 or higher GU toxicity was 11.6%.The 5-year actuarial PSA relapse-free survival rates for low-, intermediate-, and high-risk group patients, stratified according to NCCN criteria, were 100%, 91.8%, and 85.3%, respectively.Conclusions: Our initial data demonstrates the feasibility of VMAT in patients with localized prostate cancer.The rates of acute and late rectal toxicities were very low.Based on our promising initial experiences, VMAT is an established novel conformal radiation delivery method for localized prostate cancer at our institution. Further studies in a larger population are required.