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Abstract: Objective: To describe urban–rural differences in breast cancer incidence in Gharbiah, Egypt and to investigate if these differences could be explained by known risk factors of breast cancer. Methods: We used data from the population-based cancer registry of Gharbiah, Egypt to assess breast cancer incidence from 1999 through 2006. The Egyptian census provided data on district-specific population, age, and urban–rural classification. Incidence patterns of breast cancer by district and age-specific urban–rural differences were analyzed. Results: Overall, incidence rate of breast cancer was three to four times higher in urban areas than in rural areas (60.9/105-year for urban areas versus 17.8/105-year for rural areas; IRR=3.73, 95% CI=3.30, 4.22). Urban areas had consistently higher incidence of breast cancer across all age-groups for all years. Higher incidence of breast cancer was also seen in the more developed districts of Tanta and El-Mehalla. Conclusions: Higher incidence of breast cancer in urban and more developed populations might be related to higher exposure to xenoestrogens, as well as other endocrine disruptors and genotoxic substances. [ABSTRACT FROM AUTHOR]

We conducted a study in Egypt to assess the determinants of organochlorine serum levels among premenopausal women and the risk of premenopausal breast cancer for women with high organochlorine serum levels. We included 69 breast cancer patients and 53 controls consisting of visitors to the hospitals of the cancer patients. We found low levels of dichlorodiphenyldichloroethylene (DDE), total dichlorodiphenyltrichloroethane, and β-hexacholorhexane (β-HCH) in most subjects. Mean DDE levels were 12.7±20.3 ppb for cases and 16.6±30.1 ppb for controls (P=0.60); β-HCH levels were 2.1±3.8 ppb for patients and 2.1±3.9 ppb for controls (P=0.71). Interestingly, subjects with low levels had breast fed their children for an average period of 18 months. Women with no lactation history had much higher organochlorine levels than women who breast fed (P=0.002 for DDE). Younger age, older age at first childbirth, and shorter duration of breast feeding were significant predictors of higher levels of serum DDE levels. Younger age, older age at first childbirth, and higher body mass index were significant predictors of higher β-HCH levels. This study suggests that organochlorine serum levels in Egyptian women are quite low, but indicates an effect of breast feeding in eliminating organochlorines, which would imply exposure to children. Organochlorine serum level was not a risk factor of breast cancer in this population. [Copyright &y& Elsevier]

Breast cancer incidence is higher in developed countries with higher rates of estrogen receptor positive (ER+) tumors. ER+ tumors are caused by estrogenic exposures although known exposures explain approximately 50% of breast cancer risk. Unknown risk factors causing high breast cancer incidence exist that are estrogenic and development-related. Xenoestrogens are such risk factors but are difficult to study since developed countries lack unexposed populations. Developing countries have urban-rural populations with differential exposure to xenoestrogens. This study assessed urban-rural breast cancer incidence classified by hormone receptor status using data from Gharbiah population-based cancer registry in Egypt from 2001 to 2006. Urban ER+ incidence rate (per 100,000 women) was 2-4 times (IRR = 3.36, 95% CI = 4.84, 2.34) higher than rural incidence rate. ER-incidence rate was 2-3 times (IRR = 1.86, 95% CI = 2.38, 1.45) higher in urban areas than in rural areas. Our findings indicate that urban women may probably have a higher exposure to xenoestrogens.