Skipping Metastasis to Mediastinal Lymph Nodes in Non-small Cell Lung Cancer: A Clinical Study on the Reasonable Extent of Dissection.

Background: To elucidate the characteristics and metastastic pattern of skipping mediastinal lymph node metastasis (skipping N2) in non-small cell lung cancer (NSCLC), and investigate reasonable extent of lymph node dissection.

Methods: From 1990 to 1998, lobectomy combined with systematic mediastinal lymph node dissection was performed in 109 patients with NSCLC. A retrospective study was carried out to elucidate the characteristics of skipping N2 disease and to compare the difference between skipping N2 and non-skipping N2 diseases.

Results: Twenty-one patients (19%) had skipping N2 diseases. Of the skipping N2 group, 18 cases (86%) were adenocarcinoma. Skipping N2 disease was more common in T1 and T2 group than that in T3 and T4 group (P < 0.01). All skipping N2 diseases only involved one nodal station, and most of them were regional mediastinal nodal metastasis. Skipping N2 from upper lobe tumors mainly involved superior tracheobronchial or subaortic lymph nodes, and skipping N2 from lower lobe tumors involved subcarinal lymph nodes.

Conclusions: Skipping N2 disease presents certain clinical characteristics and metastastic pattern, and mediastinal nodal dissection might be modified according to the pattern.