Cancer incidence and age at northern migration of African Americans in Illinois, 1986-1991.

We compared the proportional cancer incidence of Illinois-born African Americans with those who migrated to Illinois from southern US states as children and adults, and with African American residents of the south. Adult Illinois residents, born between 1913 and 1966, who were diagnosed with cancer from 1986 through 1991 were classified by both birthplace and the state and year their social security number was assigned to determine their migration status: native, early (as child) migrant or late (as adult) migrant. African Americans of Atlanta were used to represent southern homeland ratios. Only lung cancer in African American females showed a statistically significant trend among the four groups, with Illinois native having the highest ratio. Although no trend was identified, Illinois natives had statistically significantly different ratios than both migrant groups and the southern homeland for cancers of the oral cavity (males), colon (females) and leukemias (females). The data also suggested that US regional differences in cancer ratios among African Americans exist (cancers of the prostate and testis, and in females, cancers of the oral cavity, esophagus and kidney), and among those African Americans that migrate to the north from the south, some cancer ratios also change (in males, cancers of the stomach colon, bladder and myeloma and in females, rectal cancer). Further, evidence was found in some cancer sites for the effect of the timing of northern migration on cancer risk (cancer of the rectum (males), liver (both sexes), and in females, cancer of the breast, stomach and nervous system).