BREAST-CANCER RISK-FACTORS ACCORDING TO COMBINED ESTROGEN AND PROGESTERONE-RECEPTOR STATUS - A CASE-CONTROL ANALYSIS

Breast cancers demonstrate a gradient of responsiveness to endocrine t herapy according to hormone receptor status, with tumors positive for both estrogen and progesterone receptors responding most favorably. Th e authors hypothesized that reproductive risk factors, which are proba bly mediated by endogenous hormones, would also differ according to re ceptor status, and that tumors positive for both receptors would exhib it the highest risk. information on risk factors was obtained from 1,1 54 breast cancer cases and 21,714 cancer-free controls at the Aichi Ca ncer Center Hospital, Nagoya, Japan between 1988 and 1992. Receptor st atus was known for 40% of cases, For a given risk factor, odds ratios with respect to the common control group for breast cancers of differi ng receptor status were compared using multiple polytomous logistic re gression, Risk factors did not differ significantly according to estro gen receptor status, However, age at diagnosis/interview, occupation, age at menarche, menstrual regularity at ages 20-29 years, and cigaret te smoking differed significantly or borderline significantly in effec t according to progesterone receptor status. Stratification of cases a ccording to joint estrogen and progesterone receptor status indicated that estrogen receptor status did not modify this difference in effect . This study did not support the hypothesis oi a gradient of risk for reproductive factors according to hormone receptor status. The authors recommend that the finding that some risk factors differ according to progesterone receptor status should be pursued in further studies.