A study by the NCC, Korea group. This study retrospectively analyzed 42 patients with stage I NSCLC treated with protos to an initial dose of 60 CGE in 4 fractions and sequentially modified dose 50 CGE (range 50-70 CGE), while the corresponding median biologically effective dose using 112.5 CGE (range 96-150 CGE).

At a median follow-up time of 40 months, the study reported the 3-year overall survival rate was 71.8%, the estimated rates of local control and progression free survival was 91.5% and 66.9%, respectively. Thirteen patients experienced disease progression consisting of three local, six regional, and nine distant failures. No grade 4 or 5 toxicities were observed.

This study concluded that PSPT for stage I NSCLC using SABR or hypofractionated RT was safe and showed high LC rates.