SEER is an authoritative source of information on cancer incidence and survival in the United States. SEER currently collects and publishes cancer incidence and survival data from population-based cancer registries covering approximately 28 percent of the U.S. population.
Leukemia is a cancer of the blood or bone marrow and is characterized by an abnormal proliferation (production by multiplication) of blood cells, usually white blood cells (leukocytes). This is a general term for leukemia (unknown cell type, unknown if acute or chronic).
Leukemia, NOS is a generic disease description. DCO cases or path report only cases may stay in this classification.
In most cases, NOS histology is only the provisional diagnosis; the physician will run further diagnostic procedures and look for various clinical presentations to identify a more specific leukemia. Further review of the medical record should be done to look for immunophenotyping or genetic testing that would lead to a more specific diagnosis. If the information is not available in the medical record, follow-back with the treating physician.
A more specific diagnosis would include acute leukemia, NOS as well as any specific acute or chronic leukemia. When a more specific diagnosis is identified, the histology should be changed to the more specific neoplasm name and code. See the histology tables for more information on NOS and more specific histologies.