Interlobar lymph node metastases according to primary tumor location in lung cancer.

Interlobar lymph node metastases were analyzed in consecutive 284 lung cancer patients with lobar-hilar and mediastinal lymph node dissection. Interlobar lymph node metastases were observed in 46 (16.2%) patients with no difference between right and left cases. On the right side, there was a significant difference in the frequency of inferior interlobar lymph node metastases between upper lobe and middle/lower lobe tumors (P=0.0004), but no difference in the frequencies of superior ones according to primary site. On the left, there was a significant difference in the frequency of interlobar lymph node metastases between upper lobe and lower lobe tumors (P=0.0021). In per-segment analyses, the frequency of inferior interlobar lymph node metastases in segments 1-3 and 6 was significantly lower than in the other total segments (P<0.0001) on the right, and that of interlobar lymph node metastases in the upper division segments (S1-3) was significantly lower than in the other total segments (P=0.0008) on the left. Even limited to one lobe, the patterns of interlobar lymph node metastases were different among the segments in the right lower lobe and the left upper lobe.