<TOGGLE>Chlamydia trachomatis</TOGGLE> infection as a risk factor for invasive cervical cancer

Cervical carcinoma is a sexually transmitted disease most strongly linked with human-papillomavirus (HPV) infection. We conducted a prospective sero-epidemiologic study to evaluate the role of <TOGGLE>Chlamydia trachomatis</TOGGLE> infection in the development of cervical carcinoma, with invasive cancer as an end point. A nested case-control study within a cohort of 530000 Nordic women was performed. Linking data files of 3 Nordic serum banks and the cancer registries of Finland, Norway and Sweden identified 182 women with invasive cervical carcinoma diagnosed during a mean follow-up of 5 years after serum sampling. The serum samples of the cases and matched cancer-free controls were analyzed for IgG antibodies to <TOGGLE>C. trachomatis, C. pneumoniae</TOGGLE> (a control microbe) and HPV types 16, 18 and 33, as well as for serum cotinine (an indicator of tobacco smoking). Serum antibodies to <TOGGLE>C. trachomatis</TOGGLE> were associated with an increased risk for cervical squamous-cell carcinoma (HPV- and smoking-adjusted OR, 2.2; 95% CI, 1.3–3.5). The association remained also after adjustment for smoking both in HPV16-seronegative and -seropositive cases (OR, 3.0; 95% CI, 1.8–5.1; OR, 2.3, 95% CI, 0.8–7.0 respectively). No such association was found for <TOGGLE>C. pneumoniae.</TOGGLE> Our prospective study provides sero-epidemiologic evidence that infection with <TOGGLE>C. trachomatis</TOGGLE> confers an increased risk for subsequent development of invasive squamous-cell carcinoma of the uterine cervix. Int. J. Cancer 85:35–39, 2000. © 2000 Wiley-Liss, Inc.