title: p53 and Ki-67 as markers of radioresistance in head and neck carcinoma.
abstract: BACKGROUND
  p53 and Ki-67 are regarded as potential interesting predictors of radioresistance, although their exact influence awaits confirmation on a large cohort of uniformly treated patients.
  
  
  METHODS
  In a retrospective cohort of 304 patients with squamous cell carcinoma of the head and neck who were treated with radical radiotherapy, the expression levels of p53 and Ki-67 were assessed by immunohistochemistry. Local control and survival curves were generated for p53 and Ki-67 using the Kaplan-Meier method. The difference between curves was calculated in univariate and multivariate analyses.
  
  
  RESULTS
  The overexpression of p53 was associated with local treatment failure (P = 0.01) but not with survival (P = 0.09). In a Cox analysis, p53 overexpression remained an independent predictor of local failure, with a relative risk of local failure of 1.5 (P = 0.05). Low proliferation (Ki-67 < 20%) was a significant factor in local failure for patients with tumors of the oral cavity only (P = 0.01). Patients with both unfavorable immunohistochemical markers (p53 overexpression and low proliferation) had a 45% rate of local control compared with a 67% rate for all other combinations (P = 0.002). This association was even more significant in patients with T1-T2 lesions (45% vs. 77%; P = 0.0002).
  
  
  CONCLUSIONS
  The results support the role of p53 as an independent predictor of local failure in patients with squamous cell carcinoma of the head and neck who are treated by radical radiotherapy, suggesting that it may predict radioresistance. Combined with p53, Ki-67 may help in the better selection of patients for radiotherapy, especially for patients with early-stage tumors. Prospective studies are now needed to confirm these results and to define better the role of these markers in the management of patients with head and neck carcinoma.
authors.affiliation: Service de Pathologie, CHUQ, L'Hôtel-Dieu de Québec, Québec, Canada.
authors.forename: Christian
authors.initials: C
authors.lastname: Couture
authors.forename: Hélène
authors.initials: H
authors.lastname: Raybaud-Diogène
authors.forename: Bernard
authors.initials: B
authors.lastname: Têtu
authors.forename: Isabelle
authors.initials: I
authors.lastname: Bairati
authors.forename: Danielle
authors.initials: D
authors.lastname: Murry
authors.forename: Josée
authors.initials: J
authors.lastname: Allard
authors.forename: André
authors.initials: A
authors.lastname: Fortin
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis*; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000473:pathology / Q000532:radiotherapy*; D015331:Cohort Studies; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006258:Head and Neck Neoplasms / Q000235:genetics* / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000032:analysis / Q000096:biosynthesis*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D016019:Survival Analysis; D016159:Tumor Suppressor Protein p53 / Q000032:analysis / Q000096:biosynthesis*
chemical_list: D014408:Biomarkers, Tumor; D019394:Ki-67 Antigen; D016159:Tumor Suppressor Protein p53