Most blood cancers, also called hematologic cancers, start in the bone marrow, which is where blood is produced. Blood cancers occur when abnormal blood cells start growing out of control, interrupting the function of normal blood cells, which fight off infection and produce new blood cells.

Leukemia is a blood cancer that originates in the blood and bone marrow. It occurs when the body creates too many abnormal white blood cells and interferes with the bone marrow’s ability to make red blood cells and platelets.

Non-Hodgkin lymphoma is a blood cancer that develops in the lymphatic system from cells called lymphocytes, a type of white blood cell that helps the body fight infections.

Hodgkin lymphoma is a blood cancer that develops in the lymphatic system from cells called lymphocytes. Hodgkin lymphoma is characterized by the presence of an abnormal lymphocyte called the Reed-Sternberg cell.