HILUS was a trial of SBRT for ultracentral NSCLC that had an unacceptably high rate of grade 5 adverse events with 56 Gy in 8 fractions. The trial has been dissected to identify drivers of high grade events. This study sought to identify main and intermediate bronchi DVH predictors of grade 5 airway bleeding in the HILUS cohort of 65 patients plus another 165 patients treated with the same SBRT technique off trial. Recall the prescription was typically 56 Gy in 8 fractions prescribed to the 67% isodose line. The two factors that best predicted grade 5 hemorrhage risk were near maximum dose (D0.31cc) and bronchial tumor compression (any luminal narrowing of the PBT). At 2 years, the risk of grade 5 hemorrhage was 5% at a bronchial D0.31cc of 52 Gy EQD2(3), 10% at 107 Gy, and 20% at 165 Gy. Bronchial compression had a significant influence on hemorrhage risk. Regardless of dose, bronchial compression had a baseline risk of 10% for hemorrhage–equivalent to a D0.31cc of 107 Gy. At a dose of just 58 Gy EQD2(3) in the presence of bronchial compression, the risk of grade 5 hemorrhage was 20%. | Karlsson, Int J Radiat Oncol Biol Phys 2026
