Breast Cancer Research and Treatment

, Volume 120, Issue 1, pp 149-160

First online:

Urban–rural differences in breast cancer incidence by hormone receptor status across 6 years in Egypt

  • Subhojit DeyAffiliated withDepartment of Epidemiology, School of Public Health, University of Michigan
  • , Amr S. SolimanAffiliated withDepartment of Epidemiology, School of Public Health, University of Michigan Email author 
  • , Ahmad HablasAffiliated withGharbiah Cancer Society
  • , Ibrahim A. SeifeldinAffiliated withTanta Cancer Center
  • , Kadry IsmailAffiliated withGharbiah Cancer Society
  • , Mohamed RamadanAffiliated withTanta Cancer Center
  • , Hesham El-HamzawyAffiliated withTanta Cancer Center
  • , Mark L. WilsonAffiliated withDepartment of Epidemiology, School of Public Health, University of Michigan
  • , Mousumi BanerjeeAffiliated withDepartment of Biostatistics, School of Public Health, University of Michigan
    • , Paolo BoffettaAffiliated withInternational Agency for Research on Cancer
    • , Joe HarfordAffiliated withOffice of International Affairs, National Cancer Institute
    • , Sofia D. MerajverAffiliated withUniversity of Michigan Comprehensive Cancer Center

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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.


Breast cancer incidence Hormone receptor status Mammary stem cells Xenoestrogens Egypt