One shot is all I need.
The Study: Single-fraction lung SBRT, on the other hand, just hasn’t taken off. RTOG 0915 compared 34 Gy x 1 with the 12 Gy x 4 regimen for peripheral tumors and found both to be comparable with respect to tumor control, toxicity, and survival. Unfortunately, phase 3 comparisons of these regimens got the axe—specifically the 1 fraction versus “standard” 3 fraction regimen for peripheral lesions. In this Roswell Park multi-institutional phase 2 trial, close to 100 patients were randomized to receive 30 Gy x 1 or 20 Gy x 3. Trial accrual was pretty drawn out (read: began over a decade ago) due to a 0915-hiatus, and as a result treatments largely consisted of 3D-conformal planning with fixed, co-planar fields and no heterogeneity correction. Patient selection and planning dose constraints largely matched the RTOG criteria. The grade 3 toxicity rate was roughly 15% in both groups with no grade 4+ toxicity. Local control at 2 years was roughly 95% across the board, with no differences in any survival outcomes.
TBL: Within the confines of another phase 2 trial, there appear to be no major differences in toxicity or disease outcomes for 1 fraction versus 3 fractions of lung SBRT. | Singh, Int J Radiat Oncol Biol Phys 2019