title: Human papillomavirus type 18 and rapidly progressing cervical intraepithelial neoplasia.
abstract: BACKGROUND
  Human papillomavirus type 18 (HPV-18) is the second most frequent of the HPV types detected when squamous-cell cancer is diagnosed and the type most strongly associated with adenocarcinoma of the cervix. However, in cross-sectional studies, HPV-18 is rarely detected at the time of diagnosis of high-grade cervical intraepithelial neoplasia (CIN). We used a longitudinal study design to describe the occurrence of cytological abnormality after incident HPV-18 and HPV-16 infections.
  
  
  METHODS
  The analysis was based on 1075 women aged 15-19 years, who had normal cytology and were negative for HPV at recruitment from a single family-planning clinic, and who had further follow-up. The women reattended every 6 months, and samples were taken for cytological and virological examination.
  
  
  RESULTS
  The relative risk of a cytological diagnosis of borderline nuclear abnormality after exposure to HPV-18 was 2.06 (95% CI 1.24-3.43) and that after exposure to HPV-16 was 1.99 (1.32-3.01). The relative risks of mild dyskaryosis were 3.11 (1.86-5.18) and 4.76 (3.15-7.18), and the relative risks of moderate or severe dyskaryosis were 0.80 (0.24-2.65) and 2.85 (1.36-5.97). Time to acquisition of cytological abnormality was unrelated to the infecting type (p=0.88).
  
  
  CONCLUSIONS
  Our findings do not support the long-held view that the reason why HPV-18 infection is under-represented at the time of diagnosis of high-grade CIN is because HPV-18-associated disease rapidly progresses through the preinvasive stages of neoplasia. We suggest that the cytological changes detected after HPV-18 infection might understate the severity of underlying disease. This feature could compromise the effectiveness of screening programmes in reducing the frequency of HPV-18-associated cancers.
authors.affiliation: Centre for Cancer Epidemiology, University of Manchester, Withington, M20 4QL, Manchester, UK. ciaran.woodman@cce.man.ac.uk
authors.forename: Ciaran B J
authors.initials: CB
authors.lastname: Woodman
authors.forename: Stuart
authors.initials: S
authors.lastname: Collins
authors.forename: Terry P
authors.initials: TP
authors.lastname: Rollason
authors.forename: Heather
authors.initials: H
authors.lastname: Winter
authors.forename: Andrew
authors.initials: A
authors.lastname: Bailey
authors.forename: Marie
authors.initials: M
authors.lastname: Yates
authors.forename: Lawrence S
authors.initials: LS
authors.lastname: Young
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D027383:Papillomaviridae / Q000302:isolation & purification* / Q000472:pathogenicity; D030361:Papillomavirus Infections / Q000145:classification / Q000150:complications*; D012720:Severity of Illness Index; D014412:Tumor Virus Infections / Q000145:classification / Q000150:complications*; D002578:Uterine Cervical Dysplasia / Q000175:diagnosis / Q000473:pathology / Q000821:virology*