title: The prognostic value of HPV status and p16 expression in patients with carcinoma of the anal canal.
abstract: BACKGROUND
  In anal cancer studies, the detection frequency of high-risk HPV (human papillomavirus) is variable, depending on the method used. There are limited data reporting results of different HPV detection techniques in the same clinical series, and very few correlating results with clinical outcome.
  
  
  OBJECTIVE
  To evaluate tumor expression of p16/HPV16 using three different methods, and to determine their association with clinical outcome in patients with anal canal squamous cell carcinomas (SCC).
  
  
  METHODS
  This retrospective study included patients with anal canal SCC treated with definitive radiotherapy or chemoradiotherapy at a single institution between 1992 and 2005. Formalin-fixed paraffin-embedded tumor samples from 53 of the 89 (60%) patient pre-treatment biopsies were adequate for tissue microarray construction. HPV status was determined using: p16 expression by conventional immunohistochemistry (IHC) and quantitative IHC (AQUA), HPV genotype analysis by chromogenic in situ hybridization (CISH) and HPV linear array sub-typing. Expression status was correlated with clinical outcome.
  
  
  RESULTS
  80% (28/35) of patient tumors had high p16 expression using conventional IHC. HPV16 CISH was positive in 81% (34/42) of tumors, and 78% (28/36) of tumors were HPV subtype 16. HPV16 CISH correlated with p16 evaluated by conventional IHC (correlation coefficient 0.46; p = 0.01) and by p16 AQUA score (correlation coefficient 0.49; p = 0.001). A subset of cases (15%) had very high p16 quantitative IHC scores (>244) and were associated with a higher incidence of local or distant recurrence (p = 0.04).
  
  
  CONCLUSIONS
  The vast majority (80%) of anal canal SCC in our series were positive for HPV16/p16, regardless of the testing method used. The exploratory analysis of automated quantitative IHC scoring was the only technique to define a subset of patients with a worse prognosis by p16 expression status on univariate analysis. Further exploration of the molecular mechanisms of treatment resistance in association with very high p16 expression is warranted.
authors.affiliation: Department of Medicine and Oncology, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Gloria B
authors.initials: GB
authors.lastname: Roldán Urgoiti
authors.affiliation: Department of Oncology, Tom Baker Cancer Centre, Calgary, Alberta, Canada.
authors.forename: Karla
authors.initials: K
authors.lastname: Gustafson
authors.affiliation: Department of Oncology, Tom Baker Cancer Centre, Calgary, Alberta, Canada.
authors.forename: Alexander C
authors.initials: AC
authors.lastname: Klimowicz
authors.affiliation: Department of Oncology, Tom Baker Cancer Centre, Calgary, Alberta, Canada.
authors.forename: Stephanie K
authors.initials: SK
authors.lastname: Petrillo
authors.affiliation: Department of Anatomic Pathology, H. Lee Moffitt Cancer Center, Tampa, Florida, United States of America.
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Magliocco
authors.affiliation: Department of Medicine and Oncology, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Corinne M
authors.initials: CM
authors.lastname: Doll
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D052685:Alphapapillomavirus / Q000145:classification / Q000235:genetics; D001005:Anus Neoplasms / Q000235:genetics* / Q000401:mortality / Q000473:pathology / Q000821:virology*; D014408:Biomarkers, Tumor; D019941:Cyclin-Dependent Kinase Inhibitor p16; D005260:Female; D015870:Gene Expression; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism; D030361:Papillomavirus Infections / Q000150:complications*; D063868:Patient Outcome Assessment; D011379:Prognosis; D047368:Tumor Burden
chemical_list: D014408:Biomarkers, Tumor; C000614131:CDKN2A protein, human; D019941:Cyclin-Dependent Kinase Inhibitor p16; D009363:Neoplasm Proteins