Objective: To investigate the metastatic rate of segmental and/or sub-segmental lymph nodes and their roles in pathological staging after a major pulmonary resection.
Methods: This prospective study recruited 90 cases of pulmonary resection performed at our department from February 2007 to February 2008. Hilar lymph nodes (No. 10), interlobar nodes (No. 11), lobar nodes (No. 12), segmental nodes (No. 13) and subsegmental nodes (No. 14) were resected and their clinic data analyzed.
Results: (1) The median number of total lymph nodes harvested, mediastinal nodes, nodes from No. 10-14 and nodes from No. 13-14 were 29 (11-50), 17 (6-35), 12 (2-26) and 4 (1-17) respectively. Lymph node metastatic rate from No.10, No. 11, No. 12, No. 13 + 14 were 12.2%, 6.7%, 23.3% and 38.9% respectively. (2) Forty-two cases of N0 and 27 cases of N1 were diagnosed in this group. The N1 subgroup included 12 cases of No. 13-14 metastasis solely and 15 cases of No. 10-12 and No. 13-14 metastasis simultaneously. If an analysis of No. 13-14 was omitted, the diagnostic accuracy of N0 could only reach 77.8% and 44.4% cases would be under-staged from N1. (3) In 33 cases of peripheral lung cancers smaller than 3 cm in diameter, 12.1% of metastatic lymph nodes from No.12-13 would be left in the original place if a segmental resection was performed. Similarly, 18.2% of metastatic lymph nodes could be neglected for wedge resection cases.
Conclusion: Metastasis to segmental or subsegmental lymph nodes accounts for a large part of lung cancer patients. Therefore an analysis of these nodes can improve the accuracy of pathological staging. Secondly, limited pulmonary resection needs to follow a strict indication in consideration of the potential metastasis to segmental or subsegmental lymph nodes in peripheral small lung cancers.