title: Tumour thickness as a predictor of nodal metastases in oral cancer: comparison between tongue and floor of mouth subsites.
abstract: OBJECTIVE
  To identify whether tumour thickness as a predictor of nodal metastases in oral squamous cell carcinoma differs between tongue and floor of mouth (FOM) subsites.
  
  
  METHODS
  Retrospective review of 343 patients treated between 1987 and 2012. The neck was considered positive in the presence of pathologically proven nodal metastases on neck dissection or during follow-up.
  
  
  RESULTS
  There were 222 oral tongue and 121 FOM tumours. In patients with FOM tumours 2.1-4mm thick, the rate of nodal metastases was 41.7%. In contrast, for tongue cancers of a similar thickness the rate was only 11.2%. This increased to 38.5% in patients with tongue cancers that were 4.1-6mm thick. Comparing these two subsites, FOM cancers cross the critical 20% threshold of probability for nodal metastases between 1 and 2mm whereas tongue cancers cross the 20% threshold just under 4mm thickness. On logistic regression adjusting for relevant covariates, there was a significant difference in the propensity for nodal metastases based on tumour thickness according to subsite (p=0.028).
  
  
  CONCLUSIONS
  Thin FOM tumours (2.1-4mm) have a high rate of nodal metastases. Elective neck dissection is appropriate in FOM tumours ⩾2mm thick and in tongue tumours ⩾4mm thick.
authors.affiliation: Sydney Head & Neck Cancer Institute, The Chris O'Brien Lifehouse, Missenden Road, Camperdown, NSW 2050, Australia; Department of Head & Neck Surgery, Royal Prince Alfred Hospital, Missenden Road, Camperdown, NSW 2050, Australia.
authors.forename: Deepak
authors.initials: D
authors.lastname: Balasubramanian
authors.affiliation: Sydney Head & Neck Cancer Institute, The Chris O'Brien Lifehouse, Missenden Road, Camperdown, NSW 2050, Australia; Department of Head & Neck Surgery, Royal Prince Alfred Hospital, Missenden Road, Camperdown, NSW 2050, Australia.
authors.forename: Ardalan
authors.initials: A
authors.lastname: Ebrahimi
authors.affiliation: Sydney Head & Neck Cancer Institute, The Chris O'Brien Lifehouse, Missenden Road, Camperdown, NSW 2050, Australia; Department of Tissue Pathology and Diagnostic Oncology, Royal Prince Alfred Hospital, Missenden Road, Camperdown, NSW 2050, Australia; Central Clinical School, University of Sydney, NSW 2006, Australia.
authors.forename: Ruta
authors.initials: R
authors.lastname: Gupta
authors.affiliation: Sydney Head & Neck Cancer Institute, The Chris O'Brien Lifehouse, Missenden Road, Camperdown, NSW 2050, Australia.
authors.forename: Kan
authors.initials: K
authors.lastname: Gao
authors.affiliation: Sydney Head & Neck Cancer Institute, The Chris O'Brien Lifehouse, Missenden Road, Camperdown, NSW 2050, Australia; Department of Head & Neck Surgery, Royal Prince Alfred Hospital, Missenden Road, Camperdown, NSW 2050, Australia; Central Clinical School, University of Sydney, NSW 2006, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Elliott
authors.affiliation: Sydney Head & Neck Cancer Institute, The Chris O'Brien Lifehouse, Missenden Road, Camperdown, NSW 2050, Australia; Department of Head & Neck Surgery, Royal Prince Alfred Hospital, Missenden Road, Camperdown, NSW 2050, Australia; Central Clinical School, University of Sydney, NSW 2006, Australia.
authors.forename: Carsten E
authors.initials: CE
authors.lastname: Palme
authors.affiliation: Sydney Head & Neck Cancer Institute, The Chris O'Brien Lifehouse, Missenden Road, Camperdown, NSW 2050, Australia; Department of Head & Neck Surgery, Royal Prince Alfred Hospital, Missenden Road, Camperdown, NSW 2050, Australia; Central Clinical School, University of Sydney, NSW 2006, Australia. Electronic address: jcjc@tpg.com.au.
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Clark
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; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009060:Mouth Floor / Q000473:pathology; D009062:Mouth Neoplasms / Q000473:pathology*; D009333:Neck; D009367:Neoplasm Staging; D012189:Retrospective Studies; D014062:Tongue Neoplasms / Q000473:pathology; D055815:Young Adult
keywords: Head and neck cancer; Lymph node metastases; Oral squamous cell carcinoma; Tumour thickness