Treatment patterns and results of salvage treatment for regional recurrences after stereotactic ablative radiotherapy for primary non-small cell lung cancer

Purpose: Stereotactic ablative radiotherapy (SABR) for early-stage lung cancer has shown promising results; however, regional recurrence (RR) development is not uncommon, and salvage treatment strategies have not been established. We aimed to investigate treatment patterns, prognostic factors, and survival outcomes. Materials and methods: A retrospective analysis of 391 patients who underwent SABR for primary lung cancer from 2012 to 2019 was performed. Among these patients, 90 patients showed recurrence, including local recurrence (n = 9), RR (n = 33), distant metastasis (DM) (n = 57), and RR with simultaneous DM (n = 8). The median follow-up duration was 17.3 months. Results: The median age was 75 years, and most patients underwent primary SABR due to poor lung function (69.7%). Various salvage treatments were performed in cases of RR, including chemotherapy (n = 15), radiotherapy (n = 7), concurrent chemoradiotherapy (n = 2), and best supportive care (n = 9). The median overall survival (OS) and post-recurrence OS (PR-OS) were 22.9 and 11.2 months, respectively. In multivariate analysis, age ≤75 years (HR = 0.36, p = 0.040), isolated recurrence (HR = 0.34, p = 0.037), and radiotherapy without chemotherapy (HR = 0.25, p = 0.024) were significant prognostic factors for PR-OS. Conclusions: Despite various salvage treatments, PR-OS was less than 1 year after RR in our frail patients group who underwent primary SABR. The toxicities of salvage chemotherapy could be quite severe; thus, careful patient selection is required. Further research is needed to validate our findings.