title: Progression and regression of incident cervical HPV 6, 11, 16 and 18 infections in young women.
abstract: BACKGROUND
  We describe type-specific progression, regression and persistence of incident human papillomavirus (HPV)-6-11-16 and -18 infections, along with type distribution in cervical intra-epithelial neoplasia (CIN) lesions.
  
  
  METHODS
  The study population consisted of 16-23 year-old women undergoing Pap testing and cervical swab polymerase chain reaction testing for HPV DNA at approximate 6 month intervals for up to 4 years in the placebo arm of a clinical trial of an HPV 16-vaccine. HPV types in incident infections were correlated with types in lesion biopsy specimens.
  
  
  RESULTS
  56.7% of CIN-1 and nearly one-third of CIN-2/3 lesions following incident HPV-6-11-16 or -18 infections did not correlate with the incident infection HPV type. Cumulative 36-month progression rates to CIN-2/3 testing positive for the relevant HPV type were highest for HPV-16 infections (16.5%), followed by HPV-18 (8.2%). Overall, 26.0% of CIN-1, 50.0% of CIN-2 and 70.6% of CIN-3 biopsies tested positive for HPV-6-11-16-18 infections.
  
  
  CONCLUSIONS
  Women with a given HPV type may often be co-infected or subsequently infected with other types which may lead to subsequent cervical lesions. This issue has been addressed in this study reporting data for the natural history of HPV-6-11-16 and -18 infections and is a relevant consideration in designing future studies to evaluate the incidence/risk of CIN following other type-specific HPV infections.
authors.affiliation: Department of Health Economic Statistics, Merck & Co,, Inc,, UG1C-60, P,O, Box 1000, North Wales, PA 19454-1099, USA. ralph_insinga@merck.com
authors.forename: Ralph P
authors.initials: RP
authors.lastname: Insinga
authors.forename: Erik J
authors.initials: EJ
authors.lastname: Dasbach
authors.forename: Elamin H
authors.initials: EH
authors.lastname: Elbasha
authors.forename: Kai-Li
authors.initials: KL
authors.lastname: Liaw
authors.forename: Eliav
authors.initials: E
authors.lastname: Barr