Spatially fractionated radiation (SFRT) delivers heterogeneous dose distributions within a volume with the rationale of delivering higher doses to a tumor than might otherwise be tolerable for adjacent normal tissue with a homogeneous dose distribution. In this large single institution experience, 80 patients with bulky, metastatic or unresectable tumors were treated with SFRT. The most common treatment sites were the head and neck (49%), chest (21%), and pelvis (20%). Half of cases were actually curative intent including 85% of the head and neck cases. In the majority of cases (82.9%), additional conventionally fractionated radiation was also delivered usually after SFRT. Most (62.2%) were treated with a GRID technique using a cerrobend block while the rest were treated with a LATTICE technique using helical tomotherapy. The most common prescribed dose was 20 Gy in 1 fraction (maximum point dose). The objective response rate was 82%, and locoregional recurrence at 2 years was 24%. Toxicity was relatively mild and mostly grade 2 with IMRT-based LATTICE having lower toxicity than GRID. | Wang, Int J Radiat Oncol 2025
