Sequential half-body irradiation in childhood

Abstract

Single-dose half-body irradiation (HBI), introduced for the palliation of pain from widespread bone metastases in adults, has proved to be successful. Relief is obtained in a high proportion of patients, with upwards of two-thirds experiencing complete relief. Onset of response is fast and clinically valuable duration varies from 5 to 20 weeks. Objective evidence of tumor regression is found less frequently. The dose-limiting toxicity has proved to be acute radiation pneumonitis, with bone marrow tolerance of lesser importance, in spite of the fact that many patients received previous local irradiation and/or chemotherapy. Palliative HBI has not become a valuable treatment in pediatric malignancies, because of a shorter metastatic phase. Pediatric tumors usually have shorter cell cycle times and are more responsive to systemic agents. Results are described in selected institutions, where HBI has been used in the treatment of pediatric malignancies. A single institution pilot study was undertaken at the Princess Margaret Hospital involving 17 patients with Ewing's sarcoma of bone, without overt metastases at diagnosis. Results to date have not been obviously different from overall survival in the first intergroup Ewing's sarcoma study. Overall, the treatment has been shown to be well tolerated and can be given entirely on an out-patient basis. When compared on a historical basis with a previous single dose total body irradiation study, the one year survival rate was increased. HBI appears to be a tolerable treatment, when given concurrently with or sequential to local and systemic treatment.