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

Abstract

Background: The purpose of this study is to evaluate the tolerability of hypofractionated helical tomotherapy (HT) in the treatment of localized prostate cancer.

Materials and methods: 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: 68.04 Gy at 2.52 Gy/fraction, 70 Gy at 2.5 Gy/fraction, and 70.2 Gy at 2.6 Gy/fraction. Genitourinary (GU) and gastrointestinal (GI) toxicity was scored using the Radiation Therapy Oncology Group scoring system.

Results: Thirty-two patients were treated with 68.04 Gy, 5 patients with 70 Gy, and 11 with 70.2 Gy. The median age at diagnosis was 69 years (range 49-87) and the median follow-up 11 months (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 2.6 Gy/fraction or those who received a total radiation dose ≥70 Gy had higher rates of grade ≥2 acute GU toxicity (P = 0.004 and P = 0.048, respectively).

Conclusion: 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.