title: Potential impact of a nine-valent vaccine in human papillomavirus related cervical disease.
abstract: BACKGROUND
  Information on human papillomavirus (HPV) type distribution is necessary to evaluate the potential impact of current and future HPV vaccines. We estimated the relative contribution (RC) to invasive cervical cancer (ICC) and precancerous cervical lesions of the nine HPV types (HPV 6/11/16/18/31/33/45/52/58) included in an HPV vaccine currently under development.
  
  
  METHODS
  Estimations on ICC were based on an international study of 8,977 HPV positive cases and estimations on precancerous cervical lesions were extracted from a published meta-analysis including 115,789 HPV positive women. Globocan 2008 and 2010 World Population Prospects were used to estimate current and future projections of new ICC cases.
  
  
  RESULTS
  RC of the 9 HPV types in ICC was 89.4%, with 18.5% of cases positive for HPV 31/33/45/52/58. Regional variations were observed. RCs varied by histology, ranging between 89.1% in squamous cell carcinomas (SCC) and 95.5% in adenocarcinomas (ADC). HPV 16/18/45 were detected in 94.2% of ADC. RC of the 9 types altogether decreased with age (trend test p < 0.0001), driven by the decrease in older ages of HPV 16/18/45. In contrast, the RC of HPV 31/33/52/58 increased with age. Due to population growth alone, projected estimates of ICC cases attributable to the 9 types are expected to rise from 493,770 new cases in 2012 to 560,887 new cases in 2025.The RCs of individual high risk HPV types varied by cytological and histological grades of HPV-positive precancerous cervical lesions, and there was an under representation of HPV 18 and 45 compared to ICC.
  
  
  CONCLUSIONS
  The addition of HPV 31/33/45/52/58 to HPV types included in current vaccines could prevent almost 90% of ICC cases worldwide. If the nine-valent vaccine achieves the same degree of efficacy than previous vaccines, world incidence rates could be substantially reduced.
authors.affiliation: Unit of Infections and Cancer (UNIC), Cancer Epidemiology Research Program (CERP), IDIBELL, Institut Català d'Oncologia (ICO) - Catalan Institute of Oncology, Gran Via de l'Hospitalet, 199-203, L'Hospitalet de Llobregat,, Barcelona, Spain. s.sanjose@iconcologia.net.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Serrano
authors.forename: Laia
authors.initials: L
authors.lastname: Alemany
authors.forename: Sara
authors.initials: S
authors.lastname: Tous
authors.forename: Laia
authors.initials: L
authors.lastname: Bruni
authors.forename: Gary M
authors.initials: GM
authors.lastname: Clifford
authors.forename: Thomas
authors.initials: T
authors.lastname: Weiss
authors.forename: Francesc Xavier
authors.initials: FX
authors.lastname: Bosch
authors.forename: Silvia
authors.initials: S
authors.lastname: de Sanjosé