Fig. 4.

Diagrams of the main pathways of lymphatic spread according to tumor location. a In right-side tumors, almost all RUL tumors metastasized to the RU zone directly or through the hilar lymph node. RUL tumors metastasized less frequently to the SC zone. Right lower lobe (RLL) tumors metastasized to various mediastinal lymph node zones, and skip metastasis to the RU zone was rare in RLL tumors. b In left-side tumors, all LUD tumors metastasized to the AP zone directly or through the hilar lymph node. Upper lobe tumors metastasized less frequently to the SC zone. Left lower lobe (LLL) tumors metastasized to various mediastinal lymph node zones, and skip metastasis to the AP zone was rare in LLL tumors