Hypofractionated helical tomotherapy using 2.5–2.6 Gy daily fractions for localized prostate cancer

Abstract

The purpose of this study is to evaluate the tolerability of hypofractionated helical tomotherapy (HT) in the treatment of localized prostate cancer. We evaluated 48 patients with primary adenocarcinoma of the prostate (cT1-T3N0M0) who were treated with hypofractionated HT from August 2008 through July 2011. Hypofractionated regimens included: 68.04Gy at 2.52Gy/fraction, 70Gy at 2.5Gy/fraction, and 70.2Gy at 2.6Gy/fraction. Genitourinary (GU) and gastrointestinal (GI) toxicity was scored using the Radiation Therapy Oncology Group scoring system. Thirty-two patients were treated with 68.04Gy, 5 patients with 70Gy, and 11 with 70.2Gy. The median age at diagnosis was 69years (range 49-87) and the median follow-up 11months (range 7-40). Grade 2 acute GI toxicity occurred in 9 patients (19%). No grade 3 or higher acute GI toxicity was observed. Grade 2 and 3 acute GU toxicities occurred in 19 and 6% of patients, respectively. The incidence of late grade 2 GI and GU toxicity was 4 and 2%, respectively. No grade 3 or higher late toxicities were observed. Multivariate analysis showed that patients treated at 2.6Gy/fraction or those who received a total radiation dose ≥70Gy had higher rates of grade ≥2 acute GU toxicity (P=0.004 and P=0.048, respectively). Hypofractionated HT in the treatment of localized prostate cancer is well tolerated with no grade 3 or higher early or late GI and GU toxicities. Further research is needed to assess definitive late toxicity and tumor control.