A Meta-analysis of the Efficacy of Hemi-body Irradiation
Faculty and Abstracts
Purpose: There is increasing use of novel radiation therapy in oligometastatic disease and evidence of a survival advantage for treating metastatic prostate cancer with systemic radiation using 223Ra or 177Lu-PMSA-617. Interestingly, the earliest systemic therapy for patients with bone metastases was hemibody irradiation (HBI). In this technique patients receive a single treatment to fields covering from L4 to above the skull (upper hemibody) and/or to a field covering L4 to below the feet (lower hemibody). For systemic irradiation, patients could be treated with sequential hemibody irradiation to both fields, i.e., 6 Gy upper and 8 Gy lower fields. The technique was abandoned in favor of chemotherapy and systemic radionuclides. However, with the increasing emphasis on multiple-site and systemic treatments, hemibody irradiation may again be a useful treatment. Thus we sought to employ the largest meta-analysis of the published studies on the efficacy and toxicity of HBI to date.
Methodology: A Pubmed search was done of (hemibody AND radiotherapy) and (half-body AND radiotherapy). The papers were reviewed and papers describing the efficacy and/or toxicity of the treatments were selected. These papers were reviewed using Scite for further references. The papers’ references were also reviewed for further references. The treatment protocols were evaluated and only papers using single fraction treatments to a hemibody field were abstracted. This resulted in 26 primary analyzable reports. A single factor proportional meta-analysis was performed using MetaXL®.
Results: The primary Pubmed search resulted in 313 references. Based upon the review for relevancy, 46 articles were selected. Redundant articles on the same databases and non-single HBI fraction trials were then eliminated. Reviews of the papers’ references and using Scite® resulted in 26 analyzable reports. Per the meta-analysis, 80% (95% confidence interval of 76% to 84%) of patients had a complete or partial pain response with hemibody irradiation. Among those papers that reported complete response rates, on meta-analysis 29% of patients had a complete response (CI 22% to 37%). The early treatment reports had significant acute toxicity but when better pretreatment medications and more conformal treatment techniques became available, the toxicity was reported as mild. There were no reports on long-term toxicity.
Conclusions: Hemibody irradiation is an intriguing approach to systemic irradiation of the entire skeletal system. Two fractions of hemibody irradiation have a cost of approximately US$6400, whereas a course of 226Ra costs US$180,000 and a course of 177Lu-PMSA-617 costs US$270,000. Therefore, further research into hemibody irradiation with modern techniques is warranted.
