What is Leukemia?
Leukemia is a cancer of the blood cells. There are several broad categories of blood cells, including red blood cells, white blood cells, and platelets. Generally, leukemia refers to cancers of the white blood cells.
white blood cells are a vital part of your immune system. They protect your body from invasion by:
- abnormal cells
- foreign substances
In leukemia, the white blood cells do not function like normal white blood cells. They can also divide too quickly and eventually crowd out normal cells. White blood cells are mostly produced in the bone marrow, but certain types of WBCs are also made in the lymph nodes, spleen, and thymus gland. Once formed, WBCs travel through your bloodstream and lymphatic vessels to fight infection in the body’s tissues.
The symptoms of leukemia may include:
- excessive sweating, especially at night (called “night sweats”)
- fatigue and weakness that do not go away with rest
- unintentional weight loss
- bone pain and tenderness
- painless, swollen lymph nodes (especially in the neck and armpits)
- enlarged liver or spleen
- red spots on the skin, called petechiae
- bleeding easily and bruising easily
- fever or chills
- frequent infections
The onset of leukemia can be acute (sudden onset) or chronic (slow onset). In acute leukemia, cancer cells multiply quickly. In chronic leukemia, the disease progresses slowly and early symptoms may be very mild.
Leukemia is also classified according to the type of cell that’s affected.
Leukemia involving myeloid cells is called myeloid or myelogenous leukemia. Myeloid cells are immature blood cells that would normally become granulocytes or monocytes.
Leukemia involving lymphocytes is called lymphocytic leukemia.
There are four main types of leukemia:
Acute myeloid leukemia (AML)
Acute myeloid leukemia (AML) can occur in children and adults. According to the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute (NCI), about 20,000 new cases of AML are diagnosed each year in the United States. This is the most common form of leukemia. The 5-year survival rate for AML is 29.5 percent.Acute lymphocytic leukemia (ALL)
Acute lymphocytic leukemia (ALL) occurs mostly in children. The NCI estimates about 6,000 new cases of ALL are diagnosed annually. The 5-year survival rate for ALL is 69.9 percent.Chronic myeloid leukemia (CML)
Chronic myeloid leukemia (CML) affects mostly adults. About 9,000 new cases of CML are diagnosed annually, according to the NCI. The 5-year survival rate for CML is 70.6 percent.Chronic lymphocytic leukemia (CLL)
Chronic lymphocytic leukemia (CLL) is most likely to affect people over age 55. It’s very rarely seen in children. According to the NCI, about 21,000 new cases of CLL are diagnosed annually. The 5-year survival rate for CLL is 87.2 percent. Hairy cell leukemia is a very rare subtype of CLL. Its name comes from the appearance of the cancerous lymphocytes under a microscope.
Leukemia is usually treated by a hematologist-oncologist. These are doctors who specialize in blood disorders and cancer. The treatment depends on the type and stage of the cancer. It also depends on the patient’s overall health and other medical conditions.Some forms of leukemia grow slowly and do not need immediate treatment. However, treatment for leukemia usually involves one or more of the following:
- Chemotherapy. Chemotherapy uses drugs to kill leukemia cells. Depending on the type of leukemia, you may take either a single drug or a combination of different drugs.
- Radiation therapy. Radiation therapy uses high-energy radiation to damage leukemia cells and inhibit their growth. Radiation can be applied to a specific area or to your entire body.
- Stem cell transplantation. A stem cell transplant replaces diseased bone marrow with healthy bone marrow, either your own (called autologous transplantation) or from a donor (called allogeneic transplantation). This procedure is also called a bone marrow transplant.
- Biological or immune therapy. Biological or immune therapy uses treatments that help your immune system recognize and attack cancer cells.
- Targeted therapy. Targeted therapy uses medications that take advantage of vulnerabilities in cancer cells. For example, imatinib (Gleevec) is a targeted drug that’s commonly used against CML.