Long-term Follow-up and Patterns of Recurrence of Patients With Oligometastatic NSCLC Treated With Pulmonary SBRT

Introduction: This multicenter study aims to analyze outcome as well as early versus late patterns of recurrence following pulmonary stereotactic body radiotherapy (SBRT) for patients with oligometastatic non–small-cell lung cancer (NSCLC). Materials and Methods: This analysis included 301 patients with oligometastatic NSCLC treated with SBRT for 336 lung metastases. Although treatment of the primary tumor consisted of surgical resection, radiochemotherapy, and/or systemic therapy, pulmonary oligometastases were treated with SBRT. Results: The median follow-up time was 16.1 months, resulting in 2-year overall survival (OS), local control (LC), and distant control (DC) of 62.2%, 82.0%, and 45.2%, respectively. Multivariate analysis identified age (P = .019) and histologic subtype (P = .028), as well as number of metastatic organs (P < .001) as independent prognostic factors for OS. LC was superior for patients with favorable histologic subtype (P = .046) and SBRT with a higher biological effective dose at isocenter (P = .037), whereas DC was inferior for patients with metastases in multiple organs (P < .001) and female gender (P = .027). Early (within 24 months) local or distant progression was observed in 15.3% and 36.5% of the patients. After 24 months, the risk of late local failure was low, with 3- and 4-year local failure rates of only 4.0%, and 7.6%. In contrast, patients remained at a high risk of distant progression with 3- and 4-year failure rates of 13.3% and 24.1%, respectively, with no plateau observed. Conclusion: SBRT for pulmonary oligometastatic NSCLC resulted in favorable LC and promising OS. The dominant failure pattern is distant with a continuously high risk of disease progression for many years.