Breast cancer, reproductive hormones, estrogen and progesterone receptors
Background. Carcinoma of the breast is the most prevalent cancer among Egyptian women and represents 29% of the National Cancer Institute cases. Cancer of the breast could be enhanced by many factors; one of them is estrogen, whether endogenous or exogenous. Epidemiological evidence indicates that prolonged lifetime exposure to estrogen is associated with elevated breast cancer risk in women. Aim. To study the association between breast cancer and history of intake of reproductive hormones (estrogen, progesterone and hormonal replacement therapy) among Egyptian females and identify other risk factors for breast cancer. Patients and Methods. A case-control study was carried out in the National Cancer Institute and Ain Shams University hospitals in Cairo. A total number of 351 patients were included, 198 breast cancer cases and 153 controls. All cases and controls underwent interviewing questionnaire inquiring about risk factors for breast cancer including: socio-demographic, reproductive history and environmental exposures. Anthropometric measurements, pathological staging and typing of tumour were determined. Immuno-histochemistry study was carried out to detect the profile of estrogen and progesterone receptors and blood samples were collected in order to determine the levels of estrogen and progesterone. Results. The breast cancer cases showed a statistical significant difference in comparison with the controls regarding the current or past exposure to passive smoking at home (p<0.001), higher menstrual irregularities at the age of menarche, more exposure to insecticides (p<0.05) and domestic chemicals (p<0.001), living near a factory (p<0.05), and history of exposure to breast trauma (p<0.05) and in particular brest feeding related to one of the breasts (p<0.05). No significant difference was found as regards the marital status, parity, age at menarche, age at menopause, age at first birth, lactation, body mass index grades and waist hip ratio. Higher ever use of reproductive hormones was observed among cases compared to controls (60.6%vs 52.9%) but the difference was statistically no significant (OR 1.4 CI: 0.9-2.1). The majority of breast tumours were of the ductal subtype and the profile of hormone receptors is positive for estrogen receptors and/or progesterone receptors in less than half of cases. Estrogen and progesterone receptors percentage increases with the increasing age groups. Progesterone receptor was expressed mostly among the group having no lymph nodes and no metastases involved, and its expression increases as the tumour size. No significant difference was found regarding the type of tumour and the TNM classification of breast cancer between cases with or without positive history of intake of reproductive hormones. Conclusions. Among all the epidemiological variables studied passive smoking (current and past), exposure to insecticides, domestic chemicals and breast trauma were the most significant factors associated with breast cancer. No relationship was observed between the expression of estrogen and progesterone receptors and history of intake of reproductive hormones in breast cancer cases.