Prolactin and Risk of Epithelial Ovarian Cancer.

Abstract

Prolactin is synthesized in the ovaries and may play a role in ovarian cancer etiology. One prior prospective study observed a suggestive positive association between prolactin levels and risk of ovarian cancer. We conducted a pooled case-control study of 703 cases and 864 matched controls nested within five prospective cohorts. We used unconditional logistic regression to calculate adjusted odds ratios (OR) and 95% confidence intervals (CI) for the association between prolactin and ovarian cancer risk. We examined heterogeneity by menopausal status at blood collection, body mass index (BMI), age, and histotype. Among women with known menopausal status, we observed a positive trend in the association between prolactin and ovarian cancer risk (P trend = 0.045; OR, quartile 4 vs. 1 = 1.34; 95% CI = 0.97-1.85), but no significant association was observed for premenopausal or postmenopausal women individually (corresponding OR = 1.38; 95% CI = 0.74-2.58; P trend = 0.32 and OR = 1.41; 95% CI = 0.93-2.13; P trend = 0.08, respectively; P heterogeneity = 0.91). In stratified analyses, we observed a positive association between prolactin and risk for women with BMI ≥ 25 kg/m2, but not BMI < 25 kg/m2 (corresponding OR = 2.68; 95% CI = 1.56-4.59; P trend < 0.01 and OR = 0.90; 95% CI = 0.58-1.40; P trend = 0.98, respectively; P heterogeneity < 0.01). Associations did not vary by age, postmenopausal hormone therapy use, histotype, or time between blood draw and diagnosis. We found a trend between higher prolactin levels and increased ovarian cancer risk, especially among women with a BMI ≥ 25 kg/m2. This work supports a previous study linking higher prolactin with ovarian carcinogenesis in a high adiposity setting. Future work is needed to understand the mechanism underlying this association.