Role of exogenous and endogenous sources of estrogen on the incidence of breast fibroadenoma: case-control study in Iran.

Breast fibroadenoma (FAD) is the most common benign mammary condition among women but the environmental risk factors have not identified yet. As the role of long term estrogen exposure in the incidence of FAD has been remained controversial; we have decided to investigate the possible role of endogenous and exogenous sources of estrogens in present study. Women less than 45 years old who underwent surgery from June 2009 to June 2010 were matched with controls by age and hospital. From reproductive factors, lack of breast feeding (p< 0.001, 8.76 CI95% 3.79-20.24), Nulliparity (p=0.001, OR=8.09, CI95% 3.505-18.67), Lack of parity (p=0.001, OR=6.64, CI 95% 2.56-16.31) and Hormonal dysfunction (p=0.016, OR=4.66, CI 95% 1.26- 17.28) were considered as the most important ones. Adiposity and abnormal weight gain after 18 years were considered as major background factor which induce FAD and may be contributed to the level of endogenous estrogen. Out of evaluated exogenous sources of estrogen, lower age at first OCP consumption (20.76_+3.87 vs. 22.85_+3.88, p=0.046) and living near Polycyclic aromatic hydrocarbons (PAHs) producing factories (p< 0.001, OR=3.7, CI95%1.61-7.94), were considered as the main sources of exposure to xenestrogens in FAD patients but FAD showed inverse association with cigarette smoking because of antiestrogenic activities of cigarette smoking . This study concludes that the incidence and development of FAD could be associated with the reproductive history of women, activity of ovarian hormones as well as environmental factors.

Role of xenoestrogens and endogenous sources of estrogens on the occurrence of premenopausal breast cancer in Iran.

Breast cancer affects Iranian women one decade younger than their counterparts in other countries and the underlying risk factors have remained controversial. The aryl hydrocarbon receptor (AhR) mediates endocrine disruptive activities of polyaromatic hydrocarbons (PAHs) and dioxins, which may compromise ovarian functions of women in polluted environments. This study focused on tissue expression levels of AhR and associations with exposure to chemicals with estrogen-like activities (xenoestrogens) and other reproductive factors in premenopausal breast cancer patients. Fifty cases who underwent surgery from June 2009 to June 2010 were matched with 100 controls by age and hospital records. AhR overexpression was detected in 87% of epithelial cells of young breast cancer patients. Living near factories generating PAHs and dioxins was considered as a major risk factor in premenopausal breast cancer (p=0.001, OR=4.8). History of idiopathic infertility was identified as a second significant risk factor (p=0.002, OR=3.50), which could be affected by endogenous estrogen levels. Long term (>5 yrs) consumption of oral contraceptive pills was identified as the third most important risk factor (p=0.006, OR=2.27). Adiposity and abnormal weight gain after 18 years were considered as two major background factors, which may contribute to the levels of endogenous estrogens. Direct and indirect exposure to cigarette smoke (p=0.005, OR=1.43) was considered as a weak risk factor without association with AhR levels. It seems that AhR overexpression is affected by exposure to xenoestrogens and by adiposity. Early occurrence of breast cancer in Iran may be a result of interactions between hormonal and environmental factors.