title: Lymph node ratio predicts the benefit of post-operative radiotherapy in oral cavity cancer.
abstract: BACKGROUND
  The standard treatment for non-metastatic oral cavity squamous cell carcinoma (OCSCC) is surgical resection followed by post-operative radiotherapy (PORT) with/without chemotherapy in high risk patients. Given the substantial toxicity of PORT we assessed lymph node ratio (LNR) as a predictor of PORT benefit.
  
  
  METHODS
  By using the Surveillance, Epidemiology and End Results (SEER) database, we analyzed all node positive OCSCC patients diagnosed between 1988 and 2007 who underwent neck dissection. LNR was categorized into three groups: < 6%, 6-12.5% and > 12.5%.
  
  
  RESULTS
  In 3091 subjects identified, median survival was 32, 25 and 16 months for LNR Groups 1, 2 and 3, respectively. On multivariate analysis, survival was associated with age, race, grade, tumor size, nodal stage, extra-capsular extension, use of PORT and LNR. When stratified by LNR group, PORT was associated with a survival benefit only in Group 3 (LNR > 12.5%): 2 year survival 25% vs 37%. No benefit to PORT was seen when the LNR ≤ 12.5%: 2 year survival 51% vs 54%.
  
  
  CONCLUSIONS
  A low LNR is associated with extended survival in LN positive OCSCC. The survival benefit associated with PORT in this disease appears to be limited to those with a LNR > 12.5%. Validation is required prior to the clinical implementation of our findings.
authors.affiliation: Sheba Medical Center, Ramat Gan, Israel. damien.urban@petermac.org
authors.forename: Damien
authors.initials: D
authors.lastname: Urban
authors.forename: Iris
authors.initials: I
authors.lastname: Gluck
authors.forename: M Raphael
authors.initials: MR
authors.lastname: Pfeffer
authors.forename: Zvi
authors.initials: Z
authors.lastname: Symon
authors.forename: Yaacov R
authors.initials: YR
authors.lastname: Lawrence
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D008197:Lymph Node Excision; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D018426:SEER Program