title: Population-based evidence of increased survival in human papillomavirus-related head and neck cancer.
abstract: BACKGROUND
  Evidence from clinical, population-based and molecular studies has shown that human papillomavirus (HPV) infection can be a causal risk factor for a subset of head and neck squamous cell carcinomas (HNSCC). It is proposed that HPV-associated oropharyngeal cancer is a new disease entity that requires treatment and prevention strategies distinct from present recommendations.
  
  
  METHODS
  In our population-based study we estimated incidence and survival trends in 8270 patients with HPV-related HNSCC (HPV(+)HNSCC) and HPV-unrelated HNSCC (HPV(-)HNSCC) in Norway over the past three decades.
  
  
  RESULTS
  In the period 1981-1995, patients with HPV(+)HNSCC had poorer survival than HPV(-)HNSCC (adjusted hazard ratio (HR) 1.3, 95% confidence interval (CI): 1.14-1.44). By 1996-2007, survival had increased in both groups, but the increase was significantly greater among HPV(+)HNSCC patients (HR 0.57, 95% CI: 0.48-0.67). During the same period, incidence also increased, but only for HPV(+)HNSCCs. From 1981-1995 to 1996-2007, median age at diagnosis for HPV(+)HNSCC decreased from 63.2 to 59.8 years, while for HPV(-)HNSCC median age at diagnosis of 66.6 years remained unchanged.
  
  
  CONCLUSIONS
  We demonstrate a population level improvement in survival among patients with oropharyngeal squamous cell cancers commonly related to infection with HPV. In contrast, patients with HNSCC not related to HPV only showed a modest improvement in survival in the period 1981-2007. A concomitant increase in incidence and survival was observed for HPV-related cancers only. This trend cannot be explained by changes in treatment, cancer registration nor screening, but is most likely due to an increased prevalence of HPV-positive tumours.
authors.affiliation: Department of Research, Cancer Registry of Norway, Oslo, Norway. mari.nygard@kreftregisteret.no
authors.forename: Mari
authors.initials: M
authors.lastname: Nygård
authors.forename: Bjarte
authors.initials: B
authors.lastname: Aagnes
authors.forename: Freddie
authors.initials: F
authors.lastname: Bray
authors.forename: Bjørn
authors.initials: B
authors.lastname: Møller
authors.forename: Jon
authors.initials: J
authors.lastname: Mork
mesh_terms: D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000401:mortality* / Q000821:virology*; D005260:Female; D005500:Follow-Up Studies; D006258:Head and Neck Neoplasms / Q000401:mortality* / Q000821:virology*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D027383:Papillomaviridae / Q000302:isolation & purification*; D030361:Papillomavirus Infections / Q000150:complications* / Q000401:mortality*; D012042:Registries; D012307:Risk Factors; D016019:Survival Analysis