 Levels 4, 7, 10 in both right upper and right middle lobes Levels 4, 7, 9, 10 in right lower lobe Levels 5, 6, 7 in left upper lobe Levels 7, 9, 10 in left lower lobe. or at the maximum defined as systematic radical mediastinal lymphadenectomy: all ipsilateral and easily accessible lymph-node levels must be removed, independently of the location of the primary tumour. The level of nodal sampling is as follows: Levels 2, 4, 7, 8, 9, 10 in right-sided tumours, Levels 5, 6, 7, 8, 9, 10 in left-sided tumours 