Urban-rural differences in breast cancer incidence in Egypt (1999-2006).

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 (60.9/10(5)-year for urban areas versus 17.8/10(5)-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.