Lifetime number of ovulatory cycles and epithelial ovarian cancer risk in African American women.

PURPOSE: Incessant ovulation has been consistently linked to epithelial ovarian cancer (EOC). Although reproductive characteristics differ substantially by race, the association between incessant ovulation and EOC has been evaluated only in populations of predominantly white women. In the present study, we examined the association between lifetime number of ovulatory cycles (LOCs) and EOC risk among African American (AA) women.

METHODS: We used data from 534 cases and 722 controls enrolled in the African American Cancer Epidemiology Study. LOCs were determined using the standard method, with modifications to include episodes of irregular or missed periods. Multivariable logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the association between LOCs and EOC risk overall and by age, while adjusting for appropriate confounders.

RESULTS: The mean number of LOCs was 378.2 ± 105.8 for cases and 346.4 ± 117.3 for controls. Women in the highest tertile of LOCs had 59% higher odds of EOC compared to women in the lowest tertile (OR = 1.59; 95% CI = 1.15-2.20). When examining this relationship by age, the positive association with EOC was stronger among women <50 years of age (OR for highest vs. lowest tertile = 2.61; 95% CI = 1.15-5.94), followed by women aged 50-60 years (OR = 2.27; 95% CI = 1.30-3.94). Yet, no association was present among women aged >60 years (OR = 0.79; 95% CI = 0.45-1.40).

CONCLUSIONS: In a population of AA women, we observed a positive association between LOCs and EOC risk, providing further support for the hypothesis that incessant ovulation contributes to the etiology of EOC.