Glottic tumours involving the anterior commissure in a horizontal vs vertical mode have different prognosis. Opportunity for refinement of the TNM 8th Edition

The anterior commissure (AC) represents a unique subsite of the glottic plane due to its peculiar embryological development and 3-dimensional anatomical microstructure. More than the simple junction between 2 vocal cords, in fact, the AC should be viewed as the confluence between the petiolar region and pre-epiglottic space superiorly, the anterior thirds of the false and true vocal cords and related paraglottic spaces laterally, and the conoid ligament inferiorly. These anatomical features have profound impact on the behaviour of laryngeal cancer at the level of the AC. In particular, the neoplastic patterns of growth (on the horizontal plane from one vocal fold to the contralateral one remaining on a purely glottic plane vs a vertical trans-AC extension from the supra- to the subglottis or vice versa) have distinct oncologic implications when treating these lesions by both surgical and non-surgical strategies. Therefore, the aim of this manuscript is to collect all the existing evidence in favour of the necessity to review the 8th Edition of the TNM Staging System by distinguishing tumours that involve the glottic plane without AC extension (cT1a of one and cT1b of 2 vocal cords without AC involvement) from those that encompass the AC. Based on available evidence, the prognostic implication of AC involvement should be considered in upstaging these tumours to T2, subclassifying them into T2a (horizontal involvement of the AC) and T2b (vertical trans-AC extension above and/or below the AC).