Clinicopathological characteristics and lymph node metastasis pathway of non-small-cell lung cancer located in the left lingular division.

OBJECTIVES The purpose of this study is to assess the clinicopathological characteristics of non-small-cell lung cancer (NSCLC) occurring in the left lingular division (LLD) in association with a proposal of the LLD-specific regional lymph node stations. METHODS Medical records of patients, who underwent complete tumour resection with mediastinal lymph node dissection (MLND) for LLD-NSCLC from 2000 to 2009 in multiple institutions, were retrospectively examined. We analysed patient clinicopathological characteristics and obtained the LLD-specific regional lymph node stations, and then the validity of intraoperative navigation in lymphadenectomy for LLD-NSCLC was investigated. RESULTS One hundred and eighty-four LLD-NSCLC patients (97 males and 87 females, and 128 adenocarcinomas and 56 non-adenocarcinomas) were studied. The 5-year overall survival (OS) and disease-free survival (DFS) rates for all LLD-NSCLC patients were 72.9 and 58.3%, respectively. We examined the lymph node metastasis patterns in 42 node-positive tumours. The frequent metastatic lymph node stations were #12u lobar node (n = 22), #5 subaortic node (n = 15) and #11 interlobar node (n = 13) in order. These three node stations were also single metastatic sites in some patients. Metastases to sub-carinal (#7) or inferior mediastinal nodes (#8) were rare. Thus, we assigned the three stations (#5, #11, #12u) as the regional lymph node stations for LLD-NSCLC. If these regional lymph node stations had been examined pathologically during surgery for a total of 160 LLD-NSCLC patients with c-T2N1M0 or lower stage disease, 125 p-N0 and 5 p-N1 patients diagnosed with no metastasis would have been subjected to selective MLND, while 14 p-N1 and all 16 p-N2 patients diagnosed with metastasis would have had complete MLND carried out. As a result, these regional lymph node stations could accurately predict the existence of p-N2 metastasis, and appropriately lead to a selective or complete MLND. CONCLUSIONS An intraoperative pathological examination using our proposed LLD-specific regional lymph node stations may accurately diagnose the status of node metastasis, and appropriately lead to selective or complete MLND in LLD-NSCLC patients with c-T2N1M0 or lower stage disease.