title: Patterns of extralaryngeal spread of laryngeal cancer: thyroid cartilage penetration occurs in a minority of patients with extralaryngeal spread of laryngeal squamous cell cancers.
abstract: BACKGROUND
  Laryngeal preservation programs for patients with advanced laryngeal squamous cell carcinomas (SCC) have generally excluded patients with T4 disease. The accuracy of preoperative imaging in evaluating thyroid cartilage penetration and extralaryngeal spread (ELS) has previously been questioned. Clinically, SCC spread into noncartilaginous structures may have less of a functional impact when compared with thyroid cartilage penetration. The current study was designed to characterize and quantify the routes and frequency of ELS.
  
  
  METHODS
  A total of 103 laryngectomy specimens with preoperative contrast-enhanced neck computed tomography scans were coded according to the observed extent of disease by pathological and radiological data. Previously irradiated tumors or those of pyriform sinus origin were omitted. Routes of spread were categorized as anterior (thyroid cartilage penetration), posterior (arytenoid cartilage destruction and thyroarytenoid space widening), inferior (conus elasticus penetration), and superior (base of tongue, thyrohyoid membrane or thyroid notch penetration involvement).
  
  
  RESULTS
  Sixty-three cases of ELS were identified. Anterior spread by thyroid cartilage penetration occurred in 44% of all instances of ELS, followed by both inferior and posterior spread each representing 33% of ELS cases. Superior spread occurred with a frequency of 24%.
  
  
  CONCLUSIONS
  Although thyroid cartilage penetration is a common route of ELS of glottic and supraglottic SCC, ELS into surrounding structures with thyroid cartilage penetration was found to occur in only 44% of the cases of ELS in the current study. As illustrated, advanced SCC spreads in a variety of pathways. Once these patterns are better understood and identified at the time of initial evaluation, subgroups of patients with ELS who may still be candidates for laryngeal preservation may be identified.
authors.affiliation: Department of Radiation Oncology, Emory University, Atlanta, Georgia, USA.
authors.forename: Susie A
authors.initials: SA
authors.lastname: Chen
authors.forename: Susan
authors.initials: S
authors.lastname: Muller
authors.forename: Amy Y
authors.initials: AY
authors.lastname: Chen
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Hudgins
authors.forename: Dong M
authors.initials: DM
authors.lastname: Shin
authors.forename: Fadlo
authors.initials: F
authors.lastname: Khuri
authors.forename: Nabil F
authors.initials: NF
authors.lastname: Saba
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Beitler
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D005260:Female; D006801:Humans; D007822:Laryngeal Neoplasms / Q000473:pathology*; D008297:Male; D009361:Neoplasm Invasiveness; D013957:Thyroid Cartilage / Q000473:pathology*