Palliative half-body irradiation. Single and fractionated doses

Systemic half-body irradiation (HBI) has been used extensively for the palliation of cancer pain. It has also been tried as an adjuvant therapy in patients with advanced locoregional tumors with a high propensity to disseminate and as consolidation therapy after primary systemic treatment. The limitations and toxicity of this technique have been studied extensively. Single doses of 600 rad to the upper half-body (UHB) and 800 rad to the lower half-body (LBH) have been found to achieve excellent palliative responses with an acceptable rate of complications. In order to determine the feasibility of increasing the dose of radiation delivered, a pilot study was conducted at the University of Maryland. Forty-four patients received palliative HBI. Of these, the first 36 patients received single doses to the UHB, mid-body (MB), or LHB using doses of 600 rad to the UHB and 800 rad to MB and LHB. The last consecutive eight patients received two fractions of 400 rad each, given 2-3 weeks apart. The pain response achieved by each group is similar; single dose achieved 84% complete and partial responses vs. the fractionated group, which achieved 87% complete and partial responses. The main difference between the two groups was the time necessary to achieve a response. The single dose group achieved improvement of their symptoms in 24-48 hours in approximately 70% of the patients who responded. The fractionated group achieved symptomatic response after the second dose of irradiation was given. The toxicity of both groups was similar. The acute radiation syndrome after half-body irradiation was controlled with a premedication program. Hematological toxicity was similar in both groups, and no cases of fatal radiation pneumonitis were seen. At the present time, it seems feasible to proceed with other fractionation schemes in order to try to increase the total dose delivered.