Characteristics and Outcomes of Patients With Hematological Malignancies

The pattern of hematological malignancies (HMs) in developing countries and developed countries differs. Among the different types of cancers, leukemia, lymphoma, and multiple myeloma appear to have greatly increased in frequency. These malignancies are induced by genetic damage or mutation in somatic cells, which can result from environmental exposure to chemicals, ionizing radiation, and viral agents. Comparison of the incidence of HMs across geographic regions and time is complicated by the existence of different disease classification systems, and diagnostic criteria that vary by country, and even between hospitals and cancer registries (CRs) within a country.

Leukemia is a malignant neoplasm of hematopoietic stem cells characterized by diffuse replacement of bone marrow or peripheral blood by neoplastic cells; its etiology is obscure. Leukemia typing is based on how quickly the disease develops and progresses. Leukemia is either chronic or acute. Furthermore, leukemia typing is also based on the type of white blood cell that is affected. There are 4 common types of leukemia: acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), chronic myeloid leukemia (CML), and chronic lymphocytic leukemia (CLL). Most acute leukemias are classified as lymphoid or myeloid lineages via standard microscopic morphology, cytochemistry, and immunophenotyping. Previous studies have shown that there are important differences in the incidence of the various leukemia subtypes according to geography, race/ethnicity, age, and trend pattern, indicating that the subtypes may have different etiological factors and that comprehensive global assessment of leukemia patterns is warranted.

Lymphomas are a heterogenous group of diseases with differences in epidemiology, histology, and prognosis. The incidence of Hodgkin's lymphoma (HL) and nonHodgkin's lymphoma (NHL) is higher among males than females.

Multiple myeloma (MM) is included in the spectrum of diseases ranging from monoclonal gammopathy of unknown significance (MGUS) to plasma cell leukemia. Plasma cell proliferation usually results in extensive skeletal destruction, with osteolytic lesions, hypercalcemia, anemia, and occasionally plasma cell infiltration in different organs. Excessive production of a monoclonal (M) protein can lead to renal failure, hyperviscosity syndrome, or recurrent bacterial infections.