Plasma prolactin and postmenopausal breast cancer risk: a pooled analysis of four prospective cohort studies.

Background: Prolactin, a hormone produced by the pituitary gland, regulates breast development and may contribute to breast cancer etiology. However, most epidemiologic studies of prolactin and breast cancer have been restricted to single, often small, study samples with limited exploration of effect modification.

Methods: The Biomarkers in Breast Cancer Risk Prediction consortium includes 8,279 postmenopausal women sampled from four prospective cohort studies, of whom 3,441 were diagnosed with invasive breast cancer after enrollment.

Natural menopause timing and menopause symptoms among lesbian, bisexual, and heterosexual women in the Nurses' Health Study II.

Objective: This study aimed to examine sexual orientation differences in natural menopause timing and symptoms between lesbian and bisexual women compared with heterosexual women.

Methods: We used longitudinal questionnaire data (1989-2015) from 92,314 women (858 lesbian, 375 bisexual) in the Nurses' Health Study II cohort. Women were 24-44 yr old at baseline and biennially reported their menopause status, including reasons for cessation of menstrual periods.

Plasma C-peptide mammographic features and risk of breast cancer.

Our study in the Nurses' Health Study (NHS) and NHS2, a nested case-control study with 1260 cases and 2221 controls, investigated the association between C-peptide levels, mammographic density (MD) parameters, V (a measure of gray scale variation), and breast cancer (BC) risk. We also examined how C-peptide and BC risk vary across quartiles of mammographic features. Linear and logistic regressions were used to study the associations between C-peptide and MD parameters, and breast cancer.

Circulating Estrogen Metabolites and Risk of Breast Cancer among Postmenopausal Women in the Nurses' Health Study.

Background: Estradiol and estrone are well-established risk factors for postmenopausal breast cancer (BC). Experimental evidence suggests that specific estrogen metabolites, produced via irreversible hydroxylation of estrone and estradiol at the 2- or 16-position may independently influence carcinogenesis.

Methods: We performed a nested case-control study of BC (328 BC cases; 639 controls) among postmenopausal women within the Nurses' Health Study (NHS)to examine the role of estrogens and estrogen metabolites (jointly referred to as EM).