Surgery for stage IIIA-N2 non-small cell lung cancer: the jury is still out!

Stage IIIA-N2 non-small cell lung cancer (NSCLC) comprises a very heterogeneous group of locally advanced tumors for which optimal treatment strategies remain highly controversial although results of large randomized controlled trials are available (1). In general, recommended treatment for pathologically proven, clinical stage IIIA-N2 NSCLC consists of concomitant chemoradiotherapy (CRT) (2). However, the prognosis for this patient group remains poor (3). The role of surgery in the multimodality setting is intensively debated and different treatment recommendations have been proposed. However, more recent evidence suggests that in selected patient groups neoadjuvant treatment followed by surgery yields good long-term survival with limited morbidity (4). Despite the advances in mediastinal staging and imaging techniques, a number of these patients are treated by surgical resection initially, and are found to have N2 disease only at the final pathological examination (5). This so-called “occult N2” or “surprise N2” disease occurs in around 4–10% of stage T1 and T2 tumours (6,7). The present retrospective study investigates survival and mortality rates of patients with occult N2 disease treated with initial surgery, and optimal treatment for patients with N2 disease discovered during mediastinal staging but without evidence of N2 disease on imaging studies (8). A total of 101 patients operated between 2000 and 2013 were included, which represents 3.6% of all patients who underwent lobectomy, bilobectomy or pneumonectomy during the same time period. In 30% of patients, lymph nodes >1 cm were found on chest computed tomographic (CT) scanning. Thirteen percent of patients had multilevel N2 involvement. On positron emission tomography (PET)-CT scanning 24% had positive N2 nodes. Invasive staging was performed in 43%. Most patients underwent lobectomy (83%). Adenocarcinoma was the major pathological type (72%). Adjuvant chemoradiation was completed in 86% of cases. Five- and 10-year overall survival rates were 48% and 24%, respectively. On multivariate analysis, age and peripheral vascular disease were associated with worse survival, underscoring the importance of comorbidity on final outcome. The authors conclude that patients with occult N2 disease treated with initial surgery have excellent 5-year survival rates. Furthermore, they suggest that for patients with a negative mediastinum on PET and CT scanning, but with positive N2 nodes on endobronchial ultrasound (EBUS), surgery as a first strategy in multimodal therapy should be investigated further (8)