Phase 2 nonrandomized trial of individualized stereotactic ablative radiotherapy for lung tumors

Stereotactic ablative radiotherapy (SABR) is used for treating lung tumors but can cause toxic effects, including life-threatening damage to central structures. The phase 2 nonrandomizes iSABR trial (‘individualized SABR’) assessed whether individualizing lung SABR dose and fractionation by tumor size, location, and histological characteristics may be associated with local tumor control. The trial included 217 patients with 285 treated tumors. Rates of freedom from local recurrence at 1 year were 97% for first non-small cell lung cancers (NSCLCs), 94% for new primary NSCLC with a history of prior NSCLC or multiple NSCLCs, and 96% for lung metastases from NSCLC or another tumor. These results met the primary end point of 90% or higher. The proportion of patients with grade 3 to 5 toxic effects was low at 5%, with a single possibly treatment-associated grade 5 event. The authors conclude that these results suggest that an individualized dosing regimen, including doses lower than those routinely administered, is associated with excellent tumor control.