Chlamydia trachomatis and risk of prevalent and incident cervical premalignancy in a population-based cohort.

BACKGROUND: Cofactors might affect the risk of the rare progression from infection with carcinogenic human papillomavirus (HPV) to cervical premalignancy to invasive cancer. Some studies have observed that Chlamydia trachomatis infection is associated with increased risk for cervical cancer. In a large prospective cohort, we assessed the role of C trachomatis in cervical premalignancy and addressed confounding by HPV.
METHODS: We identified 182 women with prevalent and 132 women with incident histological cervical intraepithelial neoplasia grade 2 (CIN2), grade 3 (CIN3), or cervical cancer (CIN2+) in the Costa Rica HPV Natural History Study. Control subjects were 995 (approximately 10% of the 10 049) subjects who were randomly selected from the same study. Cervical HPV status at enrollment was determined by MY09/MY11 polymerase chain reaction amplification and dot-blot hybridization. The presence of C trachomatis DNA in cervical exfoliated cells at enrollment was determined by a novel serovar-specific polymerase chain reaction-based C trachomatis detection and genotyping assay. Plasma drawn at enrollment from each subject was used to determine C trachomatis immunoglobulin G (IgG) status. Logistic regression was used to examine the association between C trachomatis and CIN2+, taking into account possible confounding by HPV.
RESULTS: C trachomatis positivity at enrollment was associated with CIN2+ and concurrent and subsequent carcinogenic HPV infection. To account for confounding by HPV status, we restricted the analysis to women positive for carcinogenic HPV DNA at enrollment and found no association between C trachomatis status (as assessed by DNA or IgG) at enrollment and combined prevalent and/or incident CIN2+ (for C trachomatis DNA positivity, odds ratio = 0.77, 95% confidence interval = 0.42 to 1.41; for C trachomatis seropositivity, odds ratio = 1.09, 95% confidence interval = 0.85 to 1.41).
CONCLUSIONS: We found no association between C trachomatis status, as assessed by DNA or IgG, and risk of cervical premalignancy, after controlling for carcinogenic HPV-positive status. Previous positive associations between C trachomatis and cervical premalignancy could have been caused, in part, by an increased susceptibility to HPV infection.