There are three main categories of blood cancers.
1) Leukemia is a type of cancer that occurs in the bone marrow (where blood is made), and in the blood itself. There are two different types of leukemia. Each type involves a large number of white blood cells. One type, called lymphocytic leukemia, involves a large number of white blood cells called lymphocytes. The other type, called myelogenous leukemia, involves a large number of white blood cells called granulocytes. White blood cells are important to help our bodies fight infection.
Leukemia can be acute or chronic. Acute leukemia develops quickly and means the body is producing a large number of white blood cells that are underdeveloped and so they cannot do their job correctly.
Chronic leukemia develops slowly and means the body is producing a large number of white blood cells that are functioning normally. Having too many white blood cells does more harm than good.
2) Lymphoma is a type of cancer that develops in the lymphatic system. The lymphatic system keeps the body fluids clean and free from infection. It is made of groups of lymph nodes (tissue masses that filter out infection-causing organisms) and vessels connecting the lymph nodes.
There are two general types of lymphoma: Hodgkin lymphoma and non-Hodgkin lymphoma. In Hodgkin lymphoma the cancer spreads from one group of lymph nodes to another in a certain order. In non-Hodgkin lymphoma the cancer spreads from one group of lymph nodes to another in a random order. There are many different types of both Hodgkin and non-Hodgkin lymphoma.
3) Myeloma is a cancer that causes the plasma cells to form a tumor in the bone marrow. Bone marrow is a soft part of the bone where blood cells (red blood cells, white blood cells, and platelets) are made. Plasma cells are white blood cells that make antibodies. Antibodies fight infections from things like bacteria, viruses, and chemicals.
Myeloma is usually found in multiple places in the body. When this happens, it is called multiple myeloma. Sometimes, myeloma is only found in one place. This is called solitary myeloma, and is rare.