Tumor-draining pulmonary vein is interrupted first and before any surgical manipulation.

Lobar arteries (+/- bronchus and inter-lobar fissures) are interrupted before tumor-draining pulmonary vein.

The pulmonary tumor-drainage vein is first exposed and punctured with a 23-gauge needle, and 7.5 ml of blood is drawn from the pulmonary vein prior to subsequent surgical manipulation for lobectomy. Collected blood is versed in a Cellsearch tube provided by the manufacturer (Menarini Silicon Biosystems, Castel Maggiore, Italy).

In the "vein first" group, the lobar vein is dissected and the cartridge and anvil of a vascular cartridge stapler are placed on either side of the vein. The vein is punctured above the stapler with a 23-gauge needle and 7.5 ml of blood is drawn. Finally, the vein is cut. The intervention then proceeds in the usual manner.

Changes in CTC count in 7.5 ml of blood sampled from the tumor-draining vein between the period before surgical manipulation (first sample) and before tumor-draining vein interruption (second sample).

Changes in CTC clusters (or CTC micro-emboli defined as ≥3 contiguous CTC) count in 7.5 ml of blood sampled from the tumor-draining vein between the period before surgical manipulation (first sample) and before tumor-draining vein interruption (second sample).

Disease free survival 2 years and 5 years after surgery and recurrence site (local or distant metastasis).

Overall survival 2 years and 5 years after surgery.