Half-body irradiation with dose escalation in the era of advanced systemic therapies: unveiling new therapeutic opportunities

Abstract Objectives To evaluate the safety and efficacy of half-body irradiation (HBI) in improving quality of life, reducing analgesic intake, alleviating pain intensity, and achieving local disease control. We hypothesized that a higher biological effective dose (BED) would increase the objective response rate (ORR) and enhance pain relief. Methods We retrospectively reviewed our mono-institutional database to identify patients with painful widespread bone metastases from solid tumors treated with HBI. Primary outcomes included pain levels, analgesic consumption, and toxicity. Secondary outcomes were ORR, local control (LC), progression-free survival (PFS), and overall survival (OS). Results Twenty-three patients met the inclusion criteria, with 24 treatments administered (one patient underwent HBI twice). Higher doses were given in 9 treatments, with 6 patients receiving a simultaneous integrated boost (SIB). Almost all patients reported immediate pain relief, with 25 % achieving complete pain resolution. Better outcomes were observed in breast cancer patients, with nearly half achieving complete pain relief. Before treatment, 82.6 % of patients used analgesics; after treatment, 42.1 % discontinued medications. Six complete responses were recorded out of 15 imaging assessments, with 5 involving higher doses. Two patients experienced local relapse, neither receiving SIB. Higher doses improved local control and pain relief, though not statistically significant. Five patients died. Three required blood transfusions due to anemia, and two had decreased platelet counts. No additional toxicity was observed in SIB-treated patients. Conclusions HBI is effective for symptom palliation in widespread bone metastases. Incorporating SIB may enhance ORR by increasing BED. Attention to marrow toxicity is needed despite radiotherapy advancements.