Spatially Fractionated Radiotherapy Combined With Immunotherapy for Advanced Solid Tumors

"Eligible patients will receive treatment using a medical linear accelerator. Within the largest tumor's gross tumor volume (GTV), spheres (0.5 - 3 cm in diameter) will be created as high - dose targets (LRT targets), spaced 2.0 - 5.0 cm apart. The LRT targets must be drawn within the GTV, avoiding blood vessels, with a margin of at least 1 cm from the GTV edge and a volume ratio of 1% - 10% of the GTV.~For a single lesion, the D95 of the GTV will be ≥1 Gy per fraction, and the D95 of the LRT target will be 8 - 12 Gy per fraction, while keeping the single - fraction dose to organs at risk as low as possible. All other irradiated metastases will receive low - dose radiotherapy at 100 - 300 cGy × 5 fractions. Brain and bone metastases will be treated with palliative radiotherapy as per clinical routine and are not included in the low - dose radiotherapy. Immunotherapy will be administered during or within one week after radiotherapy."