Geographic patterns of cancer in the population-based registry of Egypt: Possible links to environmental exposures

Background: We investigated the variation in cancer incidence in Gharbiah, Egypt to explore geographic differences in relation to demographic and environmental exposures. Methods: Using data from the only population-based cancer registry of Gharbiah, we studied the 10 most common cancers in men and women over 4 years (1999–2002). Census data provided denominators and urban–rural definitions. Crude and adjusted incidence rates (IRs), incidence rate ratios (IRRs) and 95% confidence intervals (CIs) were estimated using Poisson regression. Results: Incidence of all common cancers was higher among men than women and urban incidence was higher than rural incidence for all cancer sites. Among men and women urban–rural incidence difference was highest for prostate cancer (IRR = 4.85, 95% CI = 3.76, 6.26) and uterus (IRR = 6.05, 95% CI = 4.17, 8.78), respectively. Among men and women, El-Santa district had the highest urban–rural difference within districts for laryngeal cancer (IRR = 29.45, 95% CI = 10.63, 81.61) and uterine cancer (IRR = 15.98, 95% CI = 2.69, 95.10), respectively. El-Santa also showed the highest urban incidence among all eight districts for most cancer sites. Conclusions: Geographic differences of cancers in Gharbiah need in-depth investigation with respect to specific environmental factors that explain the geographic cancer in this region.