Follow-up periods and time-to-event outcomes were calculated from the first day of SBRT to the day that an event was confirmed. Cumulative LC rate, FFFM rate, RFS rate and OS rate were calculated from the Kaplan–Meier estimator, and then time-to-event outcomes were summarized using the Kaplan–Meier estimator with a log-rank test to compare stratified outcomes. Continuous covariates were divided at the median value to create stratification factors. Regarding BED10 for LC, other cut-off BED10 values of 106 and 150 Gy were used to create three groups: classic standard SBRT dose in Japan (48 Gy in 4 fractions) or less group (<106 Gy), higher than standard dose but less than ablative dose group (106–150 Gy) and ablative dose group (>150 Gy) [5 (link)]. The Kaplan–Meier curves were also described according to this group separation. In multivariate analyses (MVA), the Cox proportional hazards model was applied for factors with a log-rank P-value < 0.20 by using a stepwise backward elimination/forward addition approach with the Akaike information criterion (AIC) to construct the best MVA model. A P-value < 0.05 was defined as significant. Statistical analyses were performed using EZR version 1.37 (Saitama Medical Center, Jichi Medical University, Saitama, Japan), a modified version of R commander (R Foundation for Statistical Computing, Vienna, Austria) [9 (link)].