The blood cancer is  also called hematologic cancers, start within the bone marrow, which is where blood is produced. Blood cancers occur when abnormal blood cells start growing out of control and then interrupting the function of normal blood cells, which repel infection and produce new blood cells.

Types of blood cancers
The three main sorts of blood cancer are leukemia, lymphoma and myeloma:
Leukemia may be a blood cancer that originates within 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 form red blood cells and platelets.
Non-Hodgkin lymphoma may be a blood cancer that develops within the systema lymphaticum from cells called lymphocytes, a kind of white blood corpuscle that helps the body fight infections.
Hodgkin lymphoma may be a blood cancer that develops within the systema lymphaticum from cells called lymphocytes. Hodgkin lymphoma is characterized by the presence of an abnormal lymphocyte called the Reed-Sternberg cell.

Multiple myeloma may be a blood cancer that begins within the blood’s plasma cells, a kind of white blood corpuscle made within the bone marrow.