Single-fraction SBRT has obvious logistical appeal. One treatment, one day, done. However, adoption has been slow, with only about 1% of NCDB patients receiving it. This multi-institutional randomized phase 2 trial enrolled 98 medically inoperable patients with biopsy-confirmed peripheral T1–T2/N0M0 NSCLC and randomized them to 30 Gy in 1 fraction or 60 Gy in 3 fractions (20 Gy per fraction, ≥40-hour interfraction interval). Plans used 7–10 coplanar or non-coplanar beams prescribed to the 60–90% isodose line (typically 80%), normalized to the PTV center of mass. Notably, heterogeneity correction was not mandated, so delivered doses were effectively closer to 27 Gy × 1 (BED10 ~100) and 54 Gy × 3 (BED10 ~151). At a median follow-up of 35.5 months (median OS 40.3 months, only 4 patients still alive), there were no new adverse events beyond those previously reported. Grade 3+ toxicity was 16% versus 12% for the single- and three-fraction arms. There were no significant differences in freedom from local failure, freedom from distal failure, PFS, or OS. Only two local failures occurred, both in the single-fraction arm. Over 80% of patients had T1 tumors, and the authors note that small tumor volumes may have masked any dose-response difference, echoing the iSABR finding that subablative BEDs can be effective for small targets. | Singh, Int J Radiat Oncol Biol Phys 2026
