title: Is it time to incorporate 'depth of infiltration' in the T staging of oral tongue and floor of mouth cancer?
abstract: OBJECTIVE
  To summarize recent acquisitions in three-dimensional tongue and floor of mouth anatomy that can help in better evaluation of the pathways of cancer progression within these oral subsites, thus giving some hints for refining of the current TNM staging system.
  
  
  RESULTS
  The Visual Human Project is an initiative aimed at establishing a three-dimensional dataset of anatomy of two cadavers made available free to the scientific community. Visual human data have been analyzed by specific software thus improving our three-dimensional understanding of the tongue myostructure. It is already known that there is limited prognostic utility in using the two-dimensional surface diameter alone as criterion for T1-T3 definition. Recently, also the T4a categorization for the infiltration of 'deep' or extrinsic tongue muscles has been criticized. This is largely because the descriptor 'deep' does not take into account the fact that considerable portions of these muscles lie in a very superficial plane. Different prognosticators have been proposed for inclusion into the TNM staging system of oral cancer but 'depth of tumor infiltration' seems to be the most robust, universally recognized, and reproducible in the preoperative, intraoperative, and postoperative settings.
  
  
  CONCLUSIONS
  Oral tongue and floor of mouth cancer needs to be classified according to a revised TNM staging system in which 'depth of infiltration' should be taken into account. An 'ideal cut off' for distinguishing 'low' (T1-T2) from 'high-risk' (T3-T4) categories has been proposed based on the literature review, but needs retrospective as well as large prospective trials before its validation.
authors: Department of Otorhinolaryngology, Head and Neck Surgery, University of Brescia, Brescia, Italy.
authors: Cesare
authors: C
authors: Piazza
authors: Nausica
authors: N
authors: Montalto
authors: Alberto
authors: A
authors: Paderno
authors: Valentina
authors: V
authors: Taglietti
authors: Piero
authors: P
authors: Nicolai
mesh_terms: D002102:Cadaver; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D006801:Humans; D009060:Mouth Floor / Q000473:pathology* / Q000648:ultrastructure*; D009062:Mouth Neoplasms / Q000473:pathology*; D009367:Neoplasm Staging; D014059:Tongue / Q000648:ultrastructure*; D014062:Tongue Neoplasms / Q000473:pathology*