Efficacy and toxicity of hypofractionated radiation therapy for patients with hematologic malignancies: A COVID-era ILROG collaborative report

Background and purpose: During the COVID19 pandemic, shorter radiation therapy (RT) courses were needed to minimize patient exposure, ensure staff safety, and conserve healthcare resources. In response, guidelines were published by the International Lymphoma Radiation Oncology Group (ILROG) to guide treatment of hematologic malignancies patients with hypofractionated radiation therapy (hRT) regimens. However, outcomes for these hypofractionated dose/fractionation regimens in terms of efficacy and toxicity are unknown. Materials and methods: In collaboration with ILROG, we performed a retrospective multinational, multicenter study. We included patients treated from 01 January 2020 to 01 September 2020 with hRT given according to the published ILROG guidelines or hRT given at > 3 Gy per fraction. We abstracted patient and treatment data from institutional databases. CTCAE v5.0 was used to grade toxicity. Results: We included 219 patients from 8 different institutions treated with 255 RT courses. Median RT dose was 12 Gy (range 4–39) in a median of 3 fractions (range 1–13). Median follow up was 232 days, with 151 patients (69 %) alive at last follow up. Response within the RT field was assessed in 210 sites, and 127 sites (60 %) had a confirmed complete response. Maximal toxicities (per site) reported were Grade 1 (n = 48), Grade 2 (n = 25), Grade 3 (n = 3) and Grade 4 (n = 1). Grade 3/4 toxicities included dermatitis, pain, and hematologic toxicity. Conclusions: Treatment of hematologic malignancies patients with hRT was generally well tolerated with few unexpected toxicities. These data provide guidance for emergencies, and hRT may be useful and could be considered even in routine settings, especially for certain patient subgroups.