Purpose: The present study compared the complications associated with hypofractionated intensity-modulated radiation therapy (Hypo-IMRT) of prostate cancer to conventionally fractionated IMRT (Conv-IMRT).
Materials and methods: Hypo-IMRT delivered 70 Gy in 28 fractions, whereas Conv-IMRT delivered 78 Gy in 39 fractions. Toxicity was graded with the Common Terminology Criteria for Adverse Events, version 4.0, weekly during radiotherapy, 1 month after radiotherapy, and annually in both patient groups.
Results: The median follow-ups were 39.1 and 38.7 months for patients in the Hypo- and Conv-IMRT groups, respectively. There was no significant difference in rates of acute and late adverse events. The proportions of grade 2 acute genitourinary complications were 48.4 and 51.2% in the Hypo- and Conv-IMRT groups, respectively. The presence of a baseline International Prostate Symptom Score (IPSS) of ten or more was the only significant prognostic factor for grade 2 acute genitourinary toxicity. The incidence of grade 2 late rectal hemorrhage at 3 years was 3.2 and 3.5% in the Hypo- and Conv-IMRT groups, respectively. Small rectal volume was significantly associated with grade 2 late rectal hemorrhage.
Conclusion: Regarding acute and late adverse events, hypofractionated IMRT for prostate cancer was well tolerated and comparable with conventionally fractionated IMRT. Clinical trial registration no. UMIN000003218.
Keywords: Acute toxicity; Hypofractionation; Intensity modulated radiotherapy; Late toxicity; Prostate cancer.