Definitive Management of Presumed Synchronous Early Stage Non-Small Cell Lung Cancers: Outcomes and Utility of Stereotactic Ablative Radiation Therapy

Purpose: Management of synchronous early-stage non-small cell lung cancer (NSCLC) remains controversial because resection is not always feasible. This study evaluates efficacy and patterns of failure after SABR for synchronous early-stage NSCLC. Methods and Materials: From 2005 to 2015, patients presenting with ≥2 synchronous NSCLC tumors (T1a-T2b) and receiving SABR to ≥1 lesion were reviewed. The most common prescriptions were 50 Gy in 4 or 70 Gy in 10 fractions. Patients underwent multidisciplinary management with workup including chest computed tomography and positron emission tomography/computed tomography, plus brain imaging and endoscopic bronchial ultrasound for most patients to rule out mediastinal and distant disease. Synchronous lesions were defined as multiple ipsilateral or contralateral intrapulmonary lesions diagnosed within 6 months. Results: Of 912 patients treated with SABR for early-stage NSCLC at our institution, 82 (9%) presented with synchronous disease, with a total of 169 lesions. SABR was delivered to 142 lesions (84%), with 57 patients (69.5%) receiving SABR for all sites. Median overall survival (OS) and progression-free survival (PFS) were 5.1 and 2.7 years, respectively. At a median follow-up of 58 months, OS was 67% and 52% at 3 and 5 years, and corresponding PFS was 47% and 29%. Thirty-nine patients (48%) had progression, with 21 (26%) experiencing distant failure, and intralobar recurrence was among the first failure for 15 patients (18%). Of the 142 SABR-treated sites, these included 6 in-field (4%) and 4 marginal (3%) recurrences. There were no grade ≥3 adverse events. Among patients receiving SABR for all sites, there were no differences in OS (P = .946), PFS (P = .980), local control (P = .683), regional and distant control (P = .656), or toxicity (P = .791). On multivariable analysis, ipsilateral synchronous disease was associated with greater regional and distant failure (hazard ratio, 2.691; P = .025). Conclusions: Synchronous NSCLC can be managed with definitive local therapy. With high control rates and favorable outcomes, SABR is an effective and feasible treatment for synchronous early-stage NSCLC.