Adult Chronic
Also called: CLL, CML
Leukemia is cancer of the white blood cells. White blood cells help your body fight infection. Your blood cells form in your bone marrow. In leukemia, however, the bone marrow produces abnormal white blood cells. These cells crowd out the healthy blood cells, making it hard for blood to do its work.
Leukemia can develop quickly or slowly. Acute leukemia develops quickly. Chronic leukemia develops slowly. It usually occurs during or after middle age. At first, the abnormal cells still function. Eventually, however, the disease gets worse. It might cause
- Infections
- Fever
- Weight loss
- Swollen lymph nodes
- Tiredness
Detailed Guide: Leukemia - Chronic Myeloid (CML)
What Is Chronic Myeloid Leukemia (CML)?
Chronic myeloid leukemia (CML), also known as chronic myelogenous leukemia, is a type of cancer that starts in blood-forming cells of the bone marrow and invades the blood. In time, it can also invade other parts of the body, including the liver and spleen. It can also change into a fast-growing acute leukemia that invades almost any organ in the body.
Another form of chronic leukemia, called chronic lymphocytic leukemia (CLL), also starts in the bone marrow, but it starts in special cells called lymphocytes. Chronic lymphocytic leukemia is discussed in a separate American Cancer Society document.
Leukemia is different from other types of cancer that start in organs such as the lungs, colon, or breast and then spread to the bone marrow. These cancers that start elsewhere and then spread to the bone marrow are not leukemia.
Normal Bone Marrow and Lymphoid Tissue
Bone marrow is the soft inner part of some bones such as the skull, shoulder blades, ribs, pelvis, and backbones. The bone marrow is made up of blood-forming cells, fat cells, and supporting tissues that aid the growth of the blood-forming cells.
The blood-forming cells come from stem cells. These stem cells generally produce new blood-forming cells and not other kinds of cells. (This makes them different from embryonic stem cells, which are formed from a developing fetus and can develop into most other cells in the body.)
Stem cells go through a series of changes. During this process, the changing stem cells become either lymphocytes (a kind of white blood cell) or other blood-forming cells. The blood-forming cells can continue to divide or develop into 1 of the 3 main types of blood cell components: red blood cells, other types of white blood cells, or platelets. Some stem cells don’t go through these changes. Instead they divide to form new stem cells.
Red blood cells
Red blood cells contain hemoglobin, which is the substance that gives blood its red color. Hemoglobin allows the red blood cells to carry oxygen from the lungs to all other tissues in the body. Anemia (having too few red blood cells in the body) typically causes weakness, fatigue, and shortness of breath because the tissues are not getting enough oxygen.
Platelets
Platelets are actually cell fragments made by a type of bone marrow cell called the megakaryocyte. Platelets are important in plugging up holes in blood vessels caused by cuts or bruises. A shortage of platelets is called thrombocytopenia. A person with thrombocytopenia will bleed and bruise easily.
White blood cells
White blood cells are important in defending the body against infections. Lymphocytes are one type of white blood cell. The other white blood cells are monocytes, neutrophils, basophils, and eosinophils.
Lymphocytes are the main cells that make up lymphoid tissue, a major part of the immune system. Lymphoid tissue is found in lymph nodes, the thymus, the spleen, the tonsils and adenoids, and the bone marrow and is scattered throughout the digestive and respiratory systems and the bone marrow. The 2 types of lymphocytes are known as B lymphocytes (B cells) and T lymphocytes (T cells).
- B lymphocytes protect the body from invading germs by changing (maturing) into plasma cells, which produce antibodies. These antibodies attach to the germs, such as bacteria, viruses, and fungi. Once the germ has been coated in this way, granulocytes can recognize and destroy it.
- T lymphocytes can recognize cells infected by viruses and destroy these cells directly.
Neutrophils, basophils, and eosinophils are types of granulocytes - white blood cells that have granules in them, which are spots that can be seen under the microscope. These granules contain enzymes and other substances that can destroy germs that cause infections. The 3 types of granulocytes are distinguished by the size and color of their granules. Granulocytes develop from blood-forming cells called myeloblasts to become mature, infection-fighting cells. These white blood cells mainly function to destroy invading bacteria.
Any of the blood-forming or lymphoid cells from the bone marrow can turn into a leukemia cell. Once this change takes place, the leukemia cells fail to go through their normal process of maturing. Although most people think that in leukemia the cells reproduce too quickly, in most cases the problem is that they don’t die. This means that as they survive, they accumulate. Eventually, these cells spill out into the bloodstream and spread to other organs, where they can prevent other cells in the body from functioning normally.
Types of Leukemia
Not all leukemias are the same. Leukemias are divided into 4 main types with several subtypes to better predict each patient's prognosis (outlook) and to help doctors select the best treatment for each patient.
Acute leukemia versus chronic leukemia: The first factor to consider in classifying a patient's leukemia is whether most of the abnormal cells are mature (look like normal circulating white blood cells) or immature.
In acute leukemia, the bone marrow cells cannot mature properly. Immature leukemia cells continue to reproduce and build up. Without treatment, most patients with acute leukemia would live less than a few months. Some subtypes of acute leukemia respond well to treatment, and many patients are cured; however, other types of acute leukemia have a less favorable outlook.
In chronic leukemia, the cells can mature partly but not completely. They are not really normal. They generally do not fight infection as well as do normal white blood cells. And, of course, they survive longer, build up, and crowd out normal cells.
Myeloid leukemia versus lymphocytic leukemia: The second factor to consider in classifying leukemia is the type of bone marrow cells that are affected. If granulocytes or monocytes are involved, the leukemia is classified as myeloid leukemia (also known as myelocytic or myelogenous leukemia).
If the cancer develops from lymphocytes, it is called lymphocytic leukemia. (Malignant lymphomas are also cancers of lymphocytes. But, unlike lymphocytic leukemias, which develop in the bone marrow, lymphomas develop from lymphocytes in lymph nodes or other organs.)
By considering whether leukemia is acute or chronic and myeloid or lymphocytic, leukemias can be divided into these 4 main types:
- acute myeloid leukemia (AML)
- chronic myeloid leukemia (CML)
- acute lymphocytic leukemia (ALL) or acute lymphoblastic leukemia
- chronic lymphocytic leukemia (CLL)
Although almost all CML occurs in adults, it may also develop in children. Their treatment is the same as for adults.