To report toxicity (primary endpoint) and biochemical disease-free survival (BDFS) outcomes of a phase II trial evaluating ultra-hypofractionated radiation therapy (UHRT) focusing on unfavorable intermediate-risk (UIR) and high-risk (HR) prostate cancer (PCa) patients.

From 2012 to 2017, 154 patients (92 UIR or HR) were treated with helical TomoTherapy delivering 43.8-45.2 Gy in 8 fractions over 3 weeks. Seventy-three percent received hormonotherapy (51% neoadjuvant).

The median follow-up was 48 months (19-84). For the whole series, crude BDFS and 5-year BDFS were 97.4% and 94.3%, respectively. Corresponding figures for UIR and HR were 96.7% and 90%, respectively. The crude metastasis-free survival rate was 98% for the UIR and HR group. For the whole series the 5-year cumulative urinary/intestinal grade 2+ late toxicity was 17.8/7.4%. No grade 4-5 toxicity was observed. One patient experienced late grade 3 toxicity (urinary).

This 8-fraction UHRT regimen can be safely delivered to UIR/HR PCa patients. Its relapse rates are similar to those reported for the combination of external beam radiotherapy plus brachytherapy, however, the observed toxicity profile is milder. The disease survival rates compare favorably with historical controls of some other forms of radiotherapy, with similar side effects. Since the low rate of biochemical/metastasis relapse is encouraging, further research to confirm these results is justified.

BJU international. 2019 Oct 15 [Epub ahead of print]

Victor A Macias, Inmaculada Barrera-Mellado

Radiation Oncology department, Hospital Universitario y Politécnico La Fe, Valencia, Spain., Statistics department, University of Salamanca, Salamanca, Spain.