From hospital records and from death certificates, an attempt was made to assemble data on all residents of the Borough of Brooklyn diagnosed as having leukemia in the period 1943-52. A total of 1792 abstracts of hospital records and 1830 death certificates gave information on 1709 patients. The mean Brooklyn population over the same period is used to express incidences of the various forms of leukemia in relation to color, sex and age.
The incidence of leukemia in white males and females was 71.3 and 57.7 per million per annum respectively. Corresponding rates for Negroes were 46.5 and 30.6. The white-Negro difference was decreased but not eliminated by standardization to allow for differences in the age distributions of the two populations.
Sex ratios were lower for the acute forms of the disease than for the chronic forms, and, in both acute and chronic forms, for myeloid than for lymphatic cell types. No relationship of sex ratio with age at diagnosis or initial white cell count was found.
Each pathologic variety of leukemia has its own distinct age incidence curve. The lymphatic forms appear to be more sharply associated with the extremes of life than do the myeloid varieties. That is, acute lymphatic leukemia appears at a younger age than does acute myeloid leukemia and the chronic lymphatic form appears at an older average age than the chronic myeloid variety.