title: p16 and p53 Protein expression as prognostic indicators of survival and disease recurrence from head and neck cancer.
abstract: OBJECTIVE
  Markers of somatic mutation such as p16 and p53 remain controversial prognostic indicators for patients with squamous cell carcinoma of the head and neck (SCCHN). The relationship between p53 protein expression and radiation therapy is also unclear.
  
  
  METHODS
  We made a prospective cohort study (n = 171) of incident cases receiving standardized therapy for SCCHN.
  
  
  RESULTS
  Patients whose tumors showed increased p53 protein expression had over twice the risk of all-cause mortality after 550 days [hazard ratio (HR), 2.7; 95% confidence interval (CI), 1.07-6.66] and three times the risk of dying from cancer-specific causes after 550 days (HR, 3.09; 95% CI, 1.15-8.30) after adjustment for age, therapy, and stage. Tumors demonstrating alteration of both p16 and p53 did not confer any additional diagnostic information over p53 alone. Patients whose tumors expressed increased levels of p53 protein and received radiation were almost three times more likely to die as compared with those who received radiation but whose tumors did not express increased p53 protein after adjustment for age and stage (HR, 2.6; 95% CI, 1.03-6.50).
  
  
  CONCLUSIONS
  p53 protein expression was found to violate the proportional hazards assumption for our cohort, which may explain the controversial prognostic ability of this protein in the literature. p53 protein expression, but not p16 protein expression, was related to poor survival in general for men and women. In addition, an interaction between p53 expression and radiation therapy was demonstrated. Additional studies are needed to confirm and extend our results.
authors.affiliation: Department of Epidemiology, School of Public Health, University of North Carolina at Chapel Hill, USA. geislest@ohsu.edu
authors.forename: Stacy A
authors.initials: SA
authors.lastname: Geisler
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Olshan
authors.forename: Mark C
authors.initials: MC
authors.lastname: Weissler
authors.forename: Jainwen
authors.initials: J
authors.lastname: Cai
authors.forename: William K
authors.initials: WK
authors.lastname: Funkhouser
authors.forename: Joanna
authors.initials: J
authors.lastname: Smith
authors.forename: Katie
authors.initials: K
authors.lastname: Vick
mesh_terms: D000368:Aged; D015331:Cohort Studies; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000096:biosynthesis*; D005260:Female; D006258:Head and Neck Neoplasms / Q000175:diagnosis* / Q000401:mortality / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D019656:Loss of Heterozygosity; D008297:Male; D008875:Middle Aged; D009154:Mutation; D011379:Prognosis; D016016:Proportional Hazards Models; D012008:Recurrence; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis*
chemical_list: D019941:Cyclin-Dependent Kinase Inhibitor p16; D016159:Tumor Suppressor Protein p53