Hormone-related factors and risk of breast cancer in relation to estrogen receptor and progesterone receptor status

Risk factors were examined for subgroups of breast cancer characterized by estrogen receptor (ER) and progesterone receptor (PR) status. Data from the Carolina Breast Cancer Study, a population-based, North Carolina case-cont rol study of 862 breast cancer cases aged 20-74 years diagnosed during 1993 -1996 and 790 controls frequency matched on race and age, were obtained by personal interview. ER and PR status was retrieved from medical records (80 %) or was determined in the authors' laboratory (11%) but was missing for 9 % of cases. The receptor status distribution was as follows: 53% ER+PR+, 11 % ER+PR-, 8% ER-PR+, and 28% ER-PR-. Several hormone-related factors were a ssociated with stronger increased risks for ER+PR+ than for ER-PR- breast c ancer: the elevated odds ratios were strongest for ER+PR+ breast cancer amo ng postmenopausal women who had an early age at menarche (odds ratio (OR) = 1.6, 95% confidence interval (CI): 1.0, 2.4), nulliparity/late age at firs t full-term pregnancy (OR = 1.7, 95% CI: 0.9, 3.2 and OR = 1.6, 95% CI: 1.0 , 2.7, respectively), or a high body mass index (OR = 1.6, 95% CI: 0.9, 3.0 ) and among pre-/perimenopausal women who had a high waist-hip ratio (OR = 1.9, 95% CI: 1.2, 3.1). In contrast, family history of breast or ovarian ca ncer and medical radiation exposure to the chest produced higher odds ratio s for ER-PR- than for ER+PR+ breast cancer, especially among pre-/perimenop ausal women.