Background: The purpose of this study was to assess the occurrence of various morphologic types of leukemia and myeloma within patient demographic groups and to correlate findings with data-reporting periods and other variables, such as 5-year relative survival.
Methods: Data from 31,850 cases of multiple subgroups of acute and chronic leukemia, 12,237 cases of myeloma, and 321 cases of "other" lymphoreticular neoplasms were collected by the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program. The data were examined by age, sex, race, age-specific and age-adjusted incidence rate, and patient 5-year relative survival during three reporting periods: 1973-1977, 1978-1982, and 1983-1987.
Results: The age-adjusted incidence rate for all categories of leukemia combined has been constant, but there has been an increase in the relative frequency (percentage) of acute lymphoid leukemia (ALL) in the general population and a rising incidence rate of myeloid leukemia in the black population. The increase of ALL is offset by a decline of acute myeloid leukemias (AMLs) and acute leukemia, not otherwise specified. The age-adjusted rate of ALL in whites, 1.5 per 100,000 per year, is twice that of blacks, 0.8. The rates for each of the major categories of leukemia are considerably higher in males than in females. Five-year survival rates changed very little for leukemias over the 15 years of the study except for ALL, in which there was a marked improvement between the first (1973-1977) (39.1%) and second (1978-1982) (51.3%) reporting period. The SEER data confirm that multiple myeloma is predominantly a disease of late adulthood and occurs more frequently in blacks and males. The incidence rate of multiple myeloma has not changed during the 15 years surveyed. The 5-year relative survival rate has remained nearly constant for multiple myeloma. There is a marked difference in 5-year relative survival rates for patients with plasmacytoma of bone marrow (45.7%), multiple myeloma (25.9%), and plasma cell leukemia (13.0%).
Conclusions: Shifts in the relative frequencies of leukemia types may have been affected by changes in classification criteria, changes in the use of histologic terms over time, and the expanded use of immunophenotyping and other technology to characterize acute leukemias. Incidence rates and 5-year relative survival rates for myeloma have remained stable.