title: Tumor thickness and risk of lymph node metastasis in patients with squamous cell carcinoma of the tongue.
abstract: OBJECTIVE
  Oral squamous cell carcinomas, and tongue malignancies in particular, are among the most common tumors of the oral cavity. Classification for therapeutic and prognostic purposes is routinely made using the tumor, node, metastasis (TNM) system; however, current definitions do not include tumor thickness. We therefore aimed to identify variables associated with survival, and to evaluate the correlation between tumor thickness and the occurrence of lymph node metastasis.
  
  
  METHODS
  All patients undergoing radical tumor resection for squamous cell carcinomas of the tongue between 2000 and 2012 were included. Specimens were analyzed histopathologically and co-variables were interpreted. Follow-up was performed clinically and radiologically for at least 3years according to current guidelines.
  
  
  RESULTS
  We included 492 patients who had a median follow-up of 70months. Variables associated with survival (p<0.05) were age, tumor stage, N stage, UICC (Union for International Cancer Control) stage, tumor grade, and recurrence. In the receiver operating characteristic curve and Youden-Index analyses, the optimal tumor thickness cut-off was 8mm to detect significant differences in overall survival.
  
  
  CONCLUSIONS
  We highlight the importance of tumor thickness as a predictive variable in tongue cancer. Specifically, a cut-off point of 8mm allowed for a more accurate and statistically precise prediction of lymph node metastasis. These findings could supplement the current classification of tongue cancers and form the basis for treatment.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Technische Universität München, Klinikum Rechts der Isar, Germany. Electronic address: th.mucke@gmx.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Mücke
authors.affiliation: Leeds Teaching Hospitals and St James Institute of Oncology, Leeds General Infirmary, LS1 3EX, UK.
authors.forename: Anastasios
authors.initials: A
authors.lastname: Kanatas
authors.affiliation: Department of Oral and Maxillofacial Surgery, Technische Universität München, Klinikum Rechts der Isar, Germany.
authors.forename: Lucas M
authors.initials: LM
authors.lastname: Ritschl
authors.affiliation: Department of Oral and Maxillofacial Surgery, Technische Universität München, Klinikum Rechts der Isar, Germany.
authors.forename: Steffen
authors.initials: S
authors.lastname: Koerdt
authors.affiliation: Institute of Pathology, Ruhr University of Bochum, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Tannapfel
authors.affiliation: Department of Oral and Maxillofacial Surgery, Technische Universität München, Klinikum Rechts der Isar, Germany.
authors.forename: Klaus-Dietrich
authors.initials: KD
authors.lastname: Wolff
authors.affiliation: Department of Oral and Maxillofacial Surgery, Technische Universität München, Klinikum Rechts der Isar, Germany.
authors.forename: Denys
authors.initials: D
authors.lastname: Loeffelbein
authors.affiliation: Department of Oral and Maxillofacial Surgery, Technische Universität München, Klinikum Rechts der Isar, Germany.
authors.forename: Marco
authors.initials: M
authors.lastname: Kesting
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008207:Lymphatic Metastasis / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D012307:Risk Factors; D014062:Tongue Neoplasms / Q000473:pathology*; D055815:Young Adult
keywords: Cut-off point of tumor thickness; Overall survival; Prognosis; Staging; TNM