Pancoast tumor (also known as a superior sulcus tumor) is a subtype of non-small cell lung cancer that involves the apical lung and may extend outside the thoracic cavity into the root of the neck.

It may manifest as numbness and weakness of the upper limb from compression/invasion of the brachial plexus. Histologically and historically, Pancoast tumors were most commonly squamous cell carcinoma, but adenocarcinoma are now the commonest subtype.