[The pattern of mediastinal nodal involvement in lung cancer according to tumor-located lobe]

To clarify the pathway of the metastases from each pulmonary lobe to mediastinal nodes, we examined the pattern of mediastinal nodal involvement in 462 resected pN2 non-small cell lung cancer. Carcinomas of the right upper lobe frequently involved #3 (78/133) and #4 (70/133) nodes, whereas those of the right middle or lower lobe frequently metastasized to #7 nodes (18/23 and 86/113, respectively). On the other hand, carcinoma of left upper lobe frequently involved #5 nodes (81/118), whereas those of the left lower lobe most frequently metastasized to #7 nodes (50/75). Of 462 pN2 patients, 95 (20.6%) had skip metastases to the mediastinal nodes. Skip metastasis was observed more frequently in carcinomas of right upper and middle lobe. One of the reasons of skip metastasis may be the direct lymph drainage through subpleural space to mediastinum.