Level of left common carotid artery

In the IASLC lymph node map for lung cancer staging, the left common carotid artery serves as a key anatomical landmark primarily for defining the boundaries of Station 3a (prevascular) and Station 6 (para-aortic) lymph node stations, and it also helps delineate the lateral extent of the supraclavicular zone (Station 1).

• Station 3a (prevascular nodes): These nodes are located anterior to the great vessels. The left common carotid artery, along with the left subclavian artery and the brachiocephalic (innominate) artery, forms part of the posterior boundary of this station. Station 3a nodes lie anterior to these vessels and posterior to the sternum.

• Station 6 (para-aortic nodes): These nodes lie lateral to the ascending aorta or the aortic arch, anterior to the left common carotid artery origin, between a line tangential to the upper border of the aortic arch and a line tangential to the lower border of the aortic arch. The left common carotid artery thus serves as a posterior/lateral boundary for this station.

• Station 1 (supraclavicular zone): The supraclavicular nodes extend from the lower border of the cricoid cartilage to the clavicles and the upper border of the manubrium. The left common carotid artery, as it ascends from the aortic arch through the superior mediastinum into the neck, serves as a lateral/medial reference point helping to distinguish supraclavicular nodes from upper paratracheal nodes (Station 2L).