OBJECTIVETo investigate the rule of lymph node metastasis of adenosquamous carcinoma of the lung.

METHODSThe data of 361 surgically treated patients with adenosquamous carcinoma of the lung from October 1965 to June 2003 were collected and retrospectively reviewed. The classification of regional lymph node stations and TNM stage were determined according to the UICC criteria (1997). The route and patterns as well as influencing factors of lymph node metastasis were analyzed by SPSS 10.0 software. The median follow-up period was 5.5 years (range, 1.4 to 23.4 years).

RESULTSThe analysis of the route of mediastinal lymph node metastasis in the 361 cases showed that the tumor originated in the left upper lobe firstly metastasized to station 5 (A-P window), tumor in the right upper lobe to the station 4 (lower paratracheal), then secondly to station 7 (subcarinal), lastly to station 3 from the tumor in the left upper lobe or to the station 2 from the tumor in the right upper lobe. It was found that the tumors originated from the lower lobe, firstly metastasized to station 7, secondly to station 9 or 4 from the right lobe; or station 5 from left lower lobe, lastly to station 3 or 2 in the mediastinum. For the tumor in the middle lobe, mainly metastasized to station 7, 4 and 2. The skip mediastinal lymph node metastasis but N1 negative most commonly metastasized to station 7, then to station 4 from the tumor in the right lung and 5 from the tumor in the left lung. The prognosis of patients with a single skipping metastasis to mediastinal lymph node (N1-, SMLN) was better than that in the other patients with mediastinal lymph node metastases.

CONCLUSIONThe lung cancer growing in a different location has a different route and skipping metastasis to mediastinal lymph nodes. The patterns of lymph node metastasis affect prognosis. The prognosis of patients with single skipping metastasis to mediastinal lymph nodes but negative pulmonary hilar lymph node is better than that in the other patients with multiple station mediastinal lymph node metastases. The "N1-, SMLN" pattern ought to be considered as a special lymph nodal metastasis with better prognosis.