Prior <i>Chlamydia trachomatis</i> Infection and the Risk of Epithelial Ovarian Cancer and Borderline Ovarian Tumors

<h3>Background/Aim:</h3> The aim of this study was to investigate the association between serum IgG antibodies to <i>C. trachomatis</i> major outer membrane protein (MOMP), iron-binding periplasmic protein TroA, and high temperature requirement protein (HtrA), and the occurrence of epithelial ovarian cancer (EOC) and borderline ovarian tumors (BOTs). <h3>Patients and Methods:</h3> The study included patients admitted to Oulu University Hospital due to suspicion of ovarian tumor between March 2008 and May 2018. Serum IgG antibody responses to recombinant <i>C. trachomatis</i> TroA, HtrA, and MOMP were analyzed using enzyme-linked immunoassay. Oulu University Hospital medical records were obtained and reviewed. Furthermore, we assessed median carbohydrate antigen 125 levels across different <i>C. trachomatis</i> serology groups in patients with benign, BOTs, and EOCs. <h3>Results:</h3> The final study cohort consisted of 210 patients diagnosed with EOC, 46 with BOTs, and 175 with benign ovarian tumors. Among the 210 EOC cases, 40 occurred in <i>C. trachomatis</i>-seropositive patients. Of the 46 BOTs, 13 were found in the <i>C. trachomatis</i>-seropositive group. Logistic regression analysis revealed that <i>C. trachomatis</i> TroA IgG seropositivity was not associated with an increased risk of EOC (odds ratio=1.37, 95% confidence interval=0.72-2.70) but was linked to a significantly higher risk of BOTs (odds ratio=2.51, 95% confidence interval=1.02-5.98). In patients with BOTs, the median carbohydrate antigen 125 level was higher in the <i>C. trachomatis</i>-seropositive group than in the seronegative one (173 <i>vs</i>. 55 kU/l). <h3>Conclusion:</h3> Our results suggest that the presence of serum IgG antibodies against <i>C. trachomatis</i> TroA is associated with an increased risk of BOT. No association was observed between positivity for any chlamydial immunological marker and EOC risk.