Adjuvant chemotherapy following SBRT for early stage non-small cell lung cancer (NSCLC) in older patients

Abstract

Adjuvant chemotherapy improves overall survival (OS) following stereotactic body radiotherapy (SBRT) in patients with early stage non-small cell lung cancer and tumors ≥four cm. Here, we aim to evaluate its role following SBRT in older patients. Patients >70 years diagnosed with clinical stages I-II NSCLC, (N0 disease), who received SBRT, were identified using the National Cancer Database (n = 7042). The Kaplan-Meier method was used to estimate OS, and the log-rank test was used to compare distributions by treatment strategy overall and within clinical stages I and II. There were 3533 female patients (50.2%), and 6074 (86.3%) had stage I disease. Among stage I patients, 643 (10.6%) received adjuvant chemotherapy, compared to 372 stage II patients (38.4%). Median OS was better with SBRT in patients with stage I disease (25.4 vs. 20.3 months; p < .001); while patients with stage II NSCLC had better OS with SBRT + chemotherapy (20.2 vs. 14.2 months; p < .001). On multivariate analysis, patients with stage I NSCLC who received SBRT alone had better overall survival (HR: 0.79; 95% CI, 0.73, 0.87). SBRT alone was associated with an increased risk of death in patients with stage II disease (HR: 1.34; 95% CI, 1.15, 1.55). Patients with tumors ≥4 cm had better OS with SBRT + chemotherapy (18.5 vs. 15.5 months; p = .003), while patients with tumors <4 cm did better with SBRT (median OS of 24.1 vs. 20.3 months; p < .001). In >70 years old patients with tumors ≥4 cm, adjuvant chemotherapy following SBRT was associated with improved OS.