The role of minimally invasive surgery on cT4 tumours: still many unanswered question

T4 non-small-cell lung cancers (NSCLC) are a heterogeneous group of locally advanced tumours classified as stage IIIA or more in the latest TNM classification [1]. A tumour can be defined as cT4 based on many different parameters or characteristics [1]: tumour >7 cm or tumour of any size invading 1 or more of the following structures: diaphragm, mediastinum, heart, great vessels, trachea, recurrent laryngeal nerve, oesophagus, vertebral body, carina; presence of separate tumour nodule(s) in an ipsilateral lobe different from that of the primary. The 8th edition of the TNM classification reports a 5-year overall survival (OS) for cT4 of 38%, whereas OS in surgical treated series varies between 41.5 and 55% [2, 3]. In addition, subtypes of cT4 show a different prognosis with poorer survival for tumours invading the vertebral body and oesophagus, whereas better OS has been shown for additional nodules in different lobe [4]. Nodal status, age, cT4 subtype and complete resection have been demonstrated as prognostic factors in surgical resected series [3, 5]