Systemic mediastinal lymph node dissection of right lung cancer: surgical quality control and analysis of mediastinal lymph node metastatic patterns.

Standardization of systemic mediastinal lymph node dissection (SMLD) of lung cancer requires further investigation. A consecutive 124 right lung cancer patients were recruited for pulmonary resection plus SMLD. Three mediastinal lymph node compartments, (i) the upper compartment (station 1-4), (ii) the middle compartment (station 7-8) and (iii) the lower compartment (station 9), were en bloc collected to achieve surgical quality control and to analyze mediastinal lymph node metastatic patterns. The number of total harvested lymph nodes, N1 nodes and N2 nodes were 21.9+/-8.7, 9.2+/-4.7 and 12.8+/-6.7, respectively. Tumor location (peripheral or central) (P=0.023) and status of blood vessel invasion (P=0.002) were identified as risk factors for nodal involvement. Right upper lobe (RUL) cancer with N2 disease primarily metastasized to the upper compartment (27.3%) (P=0.001). For right lower lobe (RLL) cancer, lymph node metastasis most commonly detected in the middle compartment (48.8%) (P=0.001). Single mediastinal compartment metastasis occurred in 64.7% (11/17) of adenocarcinomas from RUL and RML, whereas multiple compartments metastasis occurred in all adenocarcinoma cases (12/12) from RLL (P=0.001). SMLD needs to standardize the extent of lymphadenectomy and number of removed lymph nodes for surgical quality control. Simplifying mediastinal lymph node stations to three compartments may benefit surgical excision.