Impact Of Lung Parenchymal-Only Failure On Overall Survival In Early-Stage Lung Cancer Patients Treated With Stereotactic Ablative Radiotherapy

The impact of lung parenchymal-only failure on patient survival after stereotactic body radiotherapy (SABR) for early-stage nonesmall-cell lung cancer remains unclear. Using database information of 481 patients who were treated with SABR between 2000 and 2016, we found that lung-only failure after SABR does not adversely impact overall survival. These data are useful when discussing prognosis with patients after initial SABR.Introduction: The impact of lung parenchymal-only failure on patient survival after stereotactic ablative body radiotherapy (SABR) for early-stage nonesmall-cell lung cancer (NSCLC) remains unclear. Patients and Methods: The study population included 481 patients with early-stage NSCLC who were treated with 3- to 5-fraction SABR between 2000 and 2016. The primary study objective was to assess the impact of out-of-field lung parenchymal-only failure (OLPF) on overall survival (OS). Results: At a median follow-up of 5.9 years, the median OS was 2.7 years for all patients. Patients with OLPF did not have a significantly different OS compared to patients without failure (P =.0952, median OS 4.1 years with failure vs. 2.6 years never failure). Analysis in a 1:1 propensity score-matched cohort for Karnofsky performance status, comorbidity score, and smoking status showed no differences in OS between patients without failure and those with OLPF (P =.8). In subgroup analyses exploring the impact of time of failure on OS, patients with OLPF 6 months or more after diagnosis did not have significantly different OS compared to those without failure, when accounting for immortal time bias (P =.3, median OS 4.3 years vs. 3.5 years never failure). Only 7 patients in our data set experienced failure within 6 months of treatment, of which only 4 were confirmed to be true failures; therefore, limited data are available in our cohort on the impact of OLPF for <= 6 months on OS. Conclusion: OLPF after SABR for early-stage NSCLC does not appear to adversely affect OS, especially if occurring at least 6 months after SABR. More studies are needed to understand if OLPF within 6 months of SABR is associated with adverse OS. These data are useful when discussing prognosis of lung parenchymal failures after initial SABR. (C) 2020 Elsevier Inc. All rights reserved.