BACKGROUNDTo investigate pathologically the characteristics of proximal bronchial invasion of lung cancer, and to provide the theoretic basis for the selection of a proper operation mode.

METHODSA total of 398 patients with lung carcinoma underwent radical pulmonectomy and systematic lymphadenectomy. The proximal bronchi and the hilar and mediastinal lymph nodes of their operatively resected specimens were selected for pathological study.

RESULTS(1)The direct invasion of cancerous cells through mucous, submucous or multiple layers was the most frequent way during lung cancer spread, rating 9.3%, 21.8% and 68.9% respectively. 96.4% of the cancerous invasion occurred at the proximal bronchial wall less than 1.5 cm apart from the cancer margin. The extension of invasion correlated with the histopathologic type of cancer, mode of invasion and TNM classification. (2)The cancer infiltration by the nodes metastasizing into the bronchus wall (bronchial external tunica or cartilage) was also an important way for the cancer to spread, especially in adenocarcinoma. The poor differentiated adenocarcinoma has significantly higher metastatic rate and infiltration rate than the well differentiated ( P < 0.01, P < 0.01). There were 22 such cases, including 3 of lobar bronchus wall invaded by N1 metastasis and 19 of main bronchus wall by N2 metastasis.

CONCLUSIONSFor radical removal of tumor, the key point for selecting a rational operation mode is to keep a distance of 1.5 cm or more between the excision margin of the bronchus and the tumor, to pay attention to the bronchial wall invasion caused by the metastatic lymph nodes, even in peripheral adenocarcinoma, and to dissect extensively and completely the lymph nodes of the hilar and upper and lower mediastinum at the homolateral thoracic cavity.