The rationale for every other day dosing dates back decades, but in the SBRT/SABR space was perhaps most clearly demarcated for most of us in the RTOG 0236 protocol. In this study, when delivering 54 Gy/3 it was stated that "A minimum of 40 hours and a maximum of 8 days should separate each treatmen...

I switched to daily fractionation for all SBRT prescriptions after the revised STARS trial reported the following safety outcomes with 18 Gy x 3 for peripheral or 12.5 Gy x 4 for central tumors delivered on consecutive days (n=80): "no grade 4–5 toxicity and one case each (1%) of grade 3 dyspn...