Background: Vulnerability of younger women to human papillomavirus 16 (HPV16) infection has been attributed to the predominance of ectocervical columnar epithelia in this age group. However, squamous metaplastic tissue may be more influential. We examined the extent of ectopy and metaplastic activity as risks for HPV16 acquisition in a prospective cohort.
Methods: Participants were HPV16 negative at the first two visits. Follow-up occurred every 4 months. Ectopy was quantitatively measured on colpophotographs. We calculated metaplastic rate as the difference in ectopy between visits. Cox proportional hazards models were constructed, adjusting for several covariates.
Results: Analyses included 198 women (mean baseline age 17 years) for 1734 visits. Mean follow-up was 4.4 years. Incident HPV16 was detected in 36 (18%) women. Metaplastic rate between the two visits before HPV16 detection was significantly associated with incident infection (hazard ratio [HR], 1.17; confidence interval [CI], 1.02-1.33; P = .02). However, ectopy was not significant, whether measured before or concurrent to HPV16 detection (HR range, 0.99-1.00; CI range, .97-1.02; P range, .47-.65).
Conclusions: Dynamic metaplasia rather than the sheer extent of ectopy appears to increase risk for incident HPV16 in healthy young women. This in vivo observation is consistent with the HPV life cycle, during which host cell replication and differentiation supports viral replication.