The management of stage I Non-Small cell lung cancer (NSCLC) in Ontario: A Population-Based study of patterns of care and Stereotactic Ablative Body radiotherapy (SABR) utilization from 2010 to 2019

Background: Stereotactic Ablative Body Radiotherapy (SABR) is the standard of care for medically inoperable patients with Stage I NSCLC. The adoption of SABR and its association with cancer outcomes requires characterization. Aim: We described the management of biopsy -proven Stage I NSCLC with SABR, surgery, non-SABR curative radiotherapy (RT) and observation in Ontario, Canada, between 2010 and 2019. Temporal and geographic trends in practice and survival outcomes were analyzed. Methods: This was a retrospective population -based cohort study conducted by linking electronic radiotherapy (RT) records to a population -based cancer registry. Results: A total of 12,065 patients were identified, 61.7 % underwent surgery, 17.9 % received SABR, 8.6 % received non-SABR curative RT and 11.7 % were observed. Between 2010 and 2019, the utilization of surgery decreased (63.8 % to 49.9 %, p < 0.0001), while SABR use increased (7.5 % to 24.4 %, p < 0.0001), non-SABR curative RT use increased (6.7 % to 9.6 %, p < 0.0014) and patients observed decreased (14.4 % to 12.0 %, p < 0.0001). Substantial variation in practice exists across Ontario. Two- yr CSS improved for the entire cohort (81.9 % to 85.0 %, p < 0.0001). While there was improvement in 2 yr CSS for surgical patients (92.1 %% to 95.7 %, p < 0.001), survival for patients who received SABR, Non-SABR curative RT and observation remained stable. Conclusion: There has been an increase in SABR utilization and a reduction in surgical utilization with a corresponding increased survival of stage I patients in Ontario between 2010 and 2019. Substantial differences in practice patterns exist across health regions, suggesting the need for strategies to improve access to SABR in many jurisdictions.