Purpose: Reproductive characteristics, the most established ovarian cancer risk factors, differ markedly between African-American and white women. Studies in predominantly white populations suggest that associations between reproductive characteristics and ovarian cancer vary by timing of the events and menopause status. This analysis examined associations between number, duration, and timing of reproductive events and epithelial ovarian cancer among African-American women.
Methods: Data from a multicenter case-control study of ovarian cancer in African-American women (641 cases/752 controls) were used to examine associations with oral contraceptive (OC) use and pregnancy characteristics. Odds ratios (ORs) and 95% confidence intervals (CIs) associated with reproductive characteristics were calculated with logistic regression models.
Results: OC use (OR = 0.7, 95% CI 0.5-0.9), parity (OR = 0.5, 95% CI 0.3-0.6), and breastfeeding for >12 months (OR = 0.3, 95% CI 0.2-0.5) were inversely associated with ovarian cancer. More recent pregnancies and OC use had stronger associations with ovarian cancer than pregnancies or OC use that occurred earlier in life, especially among premenopausal women.
Conclusions: This study provides the first thorough documentation that pregnancy, breastfeeding, and OC use are inversely associated with ovarian cancer in African-American women, similar to what has been observed in white women. The associations with timing of the exposures suggest that these factors have both short- and long-term effects.
Keywords: African-Americans; Breastfeeding; Case-control study; Oral contraceptives; Ovarian cancer; Parity; Pregnancy.
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