Association between late age at infectious mononucleosis, Epstein-Barr virus antibodies, and ovarian cancer risk.

We conducted two studies to evaluate the hypothesis that late age at first exposure to a common infectious agent such as Epstein-Barr virus (EBV) may be related to the risk of developing epithelial ovarian cancer. Because EBV more commonly results in infectious mononucleosis (IM) when primary infection occurs at a late age, we first assessed risk associated with age at IM in a population-based case-control study using unconditional logistic regression to estimate odds ratios and their 95% confidence intervals. Risk of ovarian cancer was 0.0, 0.9, 1.5, and 2.1 among women diagnosed with IM at < 15, 15-19, 20-24, and > 24 years, respectively, relative to women never diagnosed with IM (p for trend among women with IM = 0.02). In a second study, we examined EBV antibody titers among an independent sample of ovarian cancer cases and controls. Women with elevated IgG titers to viral capsid antigen, a marker of a relatively severe (and, conceivably, later) initial EBV infection, had a 5.3-fold (95% CI 1.5-18.4) increased risk of ovarian cancer. Together, these two studies provide some support for the hypothesis that late age at primary infection with a common agent (conceivably, EBV) may play a role in the etiology of ovarian cancer.