Real-World Clinical Outcomes and Biopsy Patterns of Older Patients with Unresected Non-Small-Cell Lung Cancer Treated with Primary Stereotactic Body Radiotherapy

<b>Background/Objectives</b>: We describe the real-world survival and utilization of lung biopsy in Medicare patients with unresected stage I-IIB (N0) non-small-cell lung cancer (NSCLC) receiving primary stereotactic body radiotherapy (SBRT) in the US. <b>Methods</b>: Patients (aged ≥66 years) with unresected stage I-IIB (N0) NSCLC who received primary SBRT were identified in the SEER-Medicare database (2007-2020) and followed from SBRT initiation until death/data end. Outcomes included overall and disease-stage-specific real-world event-free survival (rwEFS), overall survival (OS), lung cancer-specific cumulative incidence of death, and time to death or distant metastasis (TDDM). rwEFS, OS, and TDDM were described using Kaplan-Meier analysis. Median times from lung biopsy to SBRT were summarized. <b>Results</b>: Of 3014 patients (median follow-up: 2.9 years), 2302 (76.4%), 454 (15.1%), 168 (5.6%), and 90 (3.0%) had stage IA, IB, IIA, and IIB disease, respectively. The mean age at diagnosis was 77.3 years, 37.7% were male, and 86.9% were White. Overall, the 5-year rwEFS rate was 23.8% (median 26.2 months), the 5-year OS rate was 42.3% (median 48.9 months), and the 5-year lung cancer-specific cumulative incidence of death was 25.3%. rwEFS and OS rates declined with more advanced disease stage at diagnosis. Most patients (90.1%) underwent lung biopsy within 12 months before SBRT. <b>Conclusions</b>: Among older US patients with unresected NSCLC receiving SBRT, prognosis remains limited, with many deaths due to non-lung cancer causes. Recurrence and survival were lower among subgroups with more advanced disease. These findings benchmark real-world outcomes for future studies assessing novel strategies in this patient population.