Partially Ablative Body Radiation Therapy: A Widely Applicable Planning Technique for Palliation of Locally Advanced Unresectable Tumors.

Patients with locally advanced, bulky, and unresectable tumors frequently exhibit frailty and endure symptomatic burdens arising from the mass effect of their tumors. Conservative approaches may often fail to provide symptomatic benefits in relatively radioresistant, slower-growing tumors such as sarcomas. A novel technique termed partially ablative body radiation therapy (PABR) administers a highly centralized ablative dose through the utilization of a simultaneous integrated boost while delivering a low and safe palliative dose to the peripheral regions of tumors. The purpose of this paper was to describe a widely applicable radiation therapy protocol in detail for the PABR technique, of which clinical results are available in previous work. In summary, a PABR prescription of 20 Gy in 5 fractions is applied to the planning target volume and is planned for 95% of the volume to be covered by 95% of the prescribed dose. A dose of 50 Gy is planned to the boost target volume, with an allowed maximum dose of up to 65 to 70 Gy, using volumetric modulated arc therapy. Daily Cone-Beam Computed Tomography images are used for delivery verification and imaging study. The centrally located volume exceeding 50 Gy effectively achieved the desired outcomes of symptom relief and tumor size reduction. The PABR approach is widely accessible and can be readily implemented in a routine clinical setting to address a pressing need for the challenging palliative patient cohort.