Phase II study of a four-week hypofractionated external beam radiotherapy regimen for prostate cancer: Report on acute toxicity

PurposeTo evaluate the early side effects of a short course hypofractionated radiotherapy regimen in prostate cancer.Materials and methodsThree institutions (IRE, AZ VUB, GUH) included 36 patients with T1-T3N0M0 prostate cancer in a phase II study. Patients were treated with 56 Gy in 16 fractions over 4 weeks. Early side effects were scored using the RTOG/EORTC criteria and the international prostate symptom index (IPSI) weekly during treatment and 1 and 2 months afterwards. The results were compared with two control groups of patients previously treated with conventional fractionation at AZ VUB (238 patients) and GUH (114 patients).ResultsNone of the patients experienced grade 3–4 toxicity. Grade 1–2 Gastro-intestinal (GI), grade 2 GI, grade 1–2 Genito-urinary (GU) and grade 2 GU toxicity occurred in 75%, 36%, 75% and 44% for the hypofractionation schedule. The corresponding figures were 25–44%, 6–29%, 47–53% and 16–44% for the control groups (p < 0.01 for grade 1–2 GI and GU toxicity). Two months after treatment all GU and the majority of GI symptoms had resolved. The IPSI increased from (average ±1 SD) 5.6 ± 4 pre-treatment to 10.0 ± 6 during week 2–4 and had normalized (5.2 ± 4) two months after treatment.ConclusionsThough no grade 3–4 side effects were observed, the investigated schedule results in a marked increase of grade 1–2 early side effects as compared to a conventional regimen. Side effects resolved within two months post-treatment.