Relation between population density and cancer incidence, Illinois, 1986-1990.

Many investigators have examined urbanization gradients in cancer rates. The authors used incidence data for 1986 through 1990 from the Illinois State Cancer Registry, a large, population-based incidence registry, to identify race-specific, urban-rural trends in cancer rates. Using population density, they categorized an urbanization gradient into four groups. Five-year, average annual age-adjusted, site-specific incidence rates were calculated for all sex-race strata within each population density group. Monotonic and statistically significant cancer incidence trends across all race-sex groups were found for cancers of the esophagus, liver, lung, female breast and cervix, male prostate, nervous system, non-Hodgkin's lymphomas, and all cancers combined. No trend was observed for blacks that was not also seen for whites; however, significant trends for cancer of the pancreas and Hodgkin's disease were seen for whites but not for blacks. Colon cancer in males was the only sex-specific trend in cancer that can occur in both sexes. Analytic studies for sites with consistent urban-rural trends across all race-sex groups may be fruitful in identifying the aspect of population density, or other unmeasured factor, that contribute to these trends.