title: Margin to tumor thickness ratio - A predictor of local recurrence and survival in oral squamous cell carcinoma.
abstract: OBJECTIVE
  To assess whether small oral squamous cell carcinomas (OSCC) require the same margin clearance as large tumors. We evaluated the association between the ratio of the closest margin to tumor size (MSR) and tumor thickness (MTR) with local control and survival.
  
  
  METHODS
  The clinicopathologic and follow up data were obtained for 501 OSCC patients who had surgical resection with curative intent at our institution. MTR and MSR were computed and their associations with local control and survival were assessed using multivariable Cox-regression model. Survival curves were generated using the Kaplan-Meier method.
  
  
  RESULTS
  MTR was a better predictor of disease control than MSR. MTR was a predictor of local failure (p=0.033) and disease specific death (p=0.038) after adjusting for perineural invasion, lymphovascular involvement, nodal status, and radiotherapy. A threshold MTR value of 0.3 was identified, above which the risk of local recurrence was low.
  
  
  CONCLUSIONS
  The ratio of margin to tumor thickness was an independent predictor for local recurrence and disease specific death in this cohort. A MTR>0.3 can serve as a useful tool for adjuvant therapy planning as it combines tumor thickness and margin clearance, two well established prognostic factors. The minimum safe margin can be calculated by multiplying the tumor thickness by 0.3. Further prospective studies in other institutions are warranted to confirm the prognostic utility of MTR and assess the generalizability of our threshold values.
authors: Department of Head and Neck Surgery, Chris O'Brien Lifehouse, Camperdown, New South Wales, Australia; Department of Otorhinolaryngology - Head and Neck Surgery, Medical University of Vienna, Austria. Electronic address: Gregor.heiduschka@meduniwien.ac.at.
authors: Gregor
authors: G
authors: Heiduschka
authors: University of New South Wales, Randwick, New South Wales, Australia.
authors: Sohaib A
authors: SA
authors: Virk
authors: Department of Head and Neck Surgery, Chris O'Brien Lifehouse, Camperdown, New South Wales, Australia.
authors: Carsten E
authors: CE
authors: Palme
authors: Department of Head and Neck Surgery, Chris O'Brien Lifehouse, Camperdown, New South Wales, Australia; The Institute of Academic Surgery at RPA, University of Sydney, NSW, Australia.
authors: Sydney
authors: S
authors: Ch'ng
authors: Department of Head and Neck Surgery, Chris O'Brien Lifehouse, Camperdown, New South Wales, Australia.
authors: Michael
authors: M
authors: Elliot
authors: Department of Tissue Pathology and Diagnostic Oncology, Royal Prince Alfred Hospital, Camperdown, New South Wales, Australia.
authors: Ruta
authors: R
authors: Gupta
authors: Department of Head and Neck Surgery, Chris O'Brien Lifehouse, Camperdown, New South Wales, Australia; Central Clinical School, The University of Sydney, Sydney, New South Wales, Australia; South Western Sydney Clinical School, University of New South Wales, Sydney, New South Wales, Australia.
authors: Jonathan
authors: J
authors: Clark
mesh_terms: D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000473:pathology* / Q000601:surgery; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000473:pathology* / Q000601:surgery; D009364:Neoplasm Recurrence, Local / Q000473:pathology* / Q000517:prevention & control; D011379:Prognosis; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods; D016019:Survival Analysis
keywords: Margin; OSCC; Prognostic marker; Thickness