Hematology is the branch of science that deals with blood diseases as well as diseases of blood-forming organs such as spleen and bone marrow. Hematology, a sub-branch of internal medicine, basically examines diseases in two groups: benign (non-cancerous) and malignant.

Leukemia, lymphoma and multiple myeloma, which occur in the blood, bone marrow and lymph nodes, are included in the group of hematological cancers.