Survival and Resected Lymph Node Number During Sublobar Resection for N0 Non-Small Cell Lung Cancer 2 cm or Less

Background. We investigated the association between survival and the number of examined lymph nodes after sublobar resection for node-negative non-small cell lung cancer with size of 2 cm or less. Methods. The Surveillance, Epidemiology, and End Results database was used to identify patients diagnosed with non-small cell lung cancer 2 cm or less from 2004 to 2014 and underwent wedge resection or segmentectomy. Patients were stratified by the procedure (wedge resection, segmentectomy), the size of tumors (<= 1 cm, 1 to 2 cm), and the number of lymph nodes examined (0, 1 to 3, 4 to 9, >= 10). The relationship between the number of resected lymph nodes and overall survival (OS)/lung cancer-specific survival (LCSS) was analyzed. Results. A total of 2,298 patients with wedge resection and 566 patients with segmentectomy were identified. Segmentectomy was performed for bigger tumors (1.43 cm versus 1.38 cm) and was associated with more lymph nodes resected (median number: 3 versus 1). Multivariable analysis after propensity score matching revealed that lymph node resection improved survival for patients undergoing wedge resection while not for patients undergoing segmentectomy. In the wedge resection group, 1 to 3 nodes resected improved OS and 4 to 9 nodes improved OS and LCSS compared with patients without nodes evaluated for lesions 1 cm or less. No survival benefit was observed when 10 or more nodes were resected. For lesions 1 to 2 cm, incremental improvement in survival appeared with the increase of examined lymph node number. More than 16 nodes resected conferred no additional survival benefit compared with patients with 10 to 16 nodes resected. Conclusions. In wedge resection, 4 to 9 and 10 to 16 lymph nodes should be examined for lesions 1 cm or less and 1 to 2 cm, respectively. In segmentectomy, lymph node resection did not confer survival benefits for lesions 2 cm or less. (C) 2019 by The Society of Thoracic Surgeons