Leukemia (loo-KEY-me-ah) is a type of cancer in which the body produces a large number of immature, abnormally shaped blood cells. It usually affects the white blood cells, or leukocytes (LOO-ko-sites), which help the body fight infections and other diseases.
Sam had been looking forward to the basketball season for weeks. But now that it had actually started, he was having trouble keeping up during practice and in games. He just did not have the energy that he usually had, and he felt pain in his joints like never before. He found that he always needed to ask the coach to give him breaks during games. His teammates accused him of being out of shape, but Sam knew that it was more than that. His mother noticed that, even though he was playing less, he had more bruises than he did last season. Eventually, Sam had to sit out for a few weeks with a bad case of what appeared to be the flu. He constantly felt weak and tired, and he kept getting fevers. His mother decided that it was time to see the doctor and figure out what was going on.
After hearing about Sam's symptoms, the doctor ran some blood tests. These showed that Sam had leukemia, and further testing indicated that it was a type called acute lymphocytic (lim-fo-SIT-ik) leukemia, or ALL. This is the most common type of leukemia in children.
Overall, leukemia accounts for about 30 percent of cancer cases in children. Like most other types of cancer, it is much more common in adults. More than 54,270 adults and about 2,700 teenagers and children in the United States are diagnosed with leukemia each year.
Leukemia is a type of cancer that affects the bone marrow, which is the soft, spongy center of the bone that produces most of the three types of cells in the blood. They are as follows:
Normally, the marrow produces these cells in an orderly, controlled way as the body needs them. With leukemia, the process gets out of control. In most cases, the marrow produces too many immature white blood cells (called blasts) that are abnormally shaped and cannot carry out their usual duties. This symptom explains why the disease is called leukemia, which literally means “white blood.” As these blasts multiply and crowd the bone marrow, they interfere with the production of other types of blood cells. When the blasts move into the body, they can collect in different places, causing swelling or pain.
Different types of leukemia:
In all, the disease has four main forms: acute lymphocytic leukemia (ALL), acute myelogenous leukemia (AML), chronic lymphocytic leukemia (CLL), and chronic myelogenous leukemia (CML). Another less common form is called hairy cell leukemia, a chronic condition in which the cells develop projections that look like tiny hairs.
In most cases of leukemia, doctors cannot pinpoint a specific cause. Researchers have identified a few possible risk factors * . Studies have shown that people who are exposed to high or repeated doses of radiation * , such as Japanese survivors of the atomic bomb dropped at Hiroshima during World War II, and people with other types of cancer who have been treated with radiation therapy * , are more likely to develop leukemia. Workers who are exposed to certain chemicals, such as benzene that is used in certain manufacturing processes, develop leukemia more frequently. In addition, researchers have been exploring whether certain viruses may play a role in the disease.
Researchers are also examining how a person's genes * may be involved in causing leukemia. In studying the cells of people who have the disease, researchers have found that they often share certain genetic abnormalities.
Some people have suggested a possible connection between childhood leukemia and the low-energy waves given off by high-voltage electric power lines, but numerous studies have not shown a relationship.
When someone has leukemia, the abnormal, immature white blood cells that form cannot help the body fight off infections. As a result, the person may have frequent infections and develop flulike symptoms, such as fever and chills. As these cells keep multiplying and move out into the body, they tend to collect in the lymph nodes * or in organs such as the liver * or spleen * . This symptom may cause pain and swelling. If the cells collect in the central nervous system (the brain and spinal cord), the person may experience headaches, vomiting, confusion, loss of muscle control, or seizures.
The oversupply of white blood cells interferes with the normal production of red blood cells and platelets, causing bleeding problems and a condition called anemia (a-NEE-me-ah). Individuals may look pale or feel weak and tired. They may also bleed or bruise easily or find that their gums are swollen or bleeding. Other possible symptoms of leukemia include loss of appetite and/or weight; tiny red spots under the skin; sweating, especially at night; and bone or joint pain.
Medical professionals can sometimes detect chronic leukemia through a routine blood test before symptoms appear. Doctors who see patients presenting symptoms characteristic of leukemia usually start by doing a full physical exam and feeling for swelling in the liver; in the spleen; and in the lymph nodes under the arms, in the groin, and in the neck. They may also take a sample of blood and examine it under a microscope to see what the cells look like and to determine the ratio of mature cells to immature cells. Although blood tests may reveal that a patient has leukemia, they may not show what type it is. To check further for leukemia cells or to identify what type of leukemia a patient has, a doctor may have to perform a bone marrow aspiration * . In this test, the doctor inserts a needle into a large bone, usually the hip, and removes a small sample of bone marrow to examine under a microscope for leukemia cells.
If leukemia is present, the doctor may order additional tests to look for abnormal cells in other parts of the body. A spinal tap involves taking a sample of the fluid that fills the spaces in and around the brain and spinal cord so that it can be checked for leukemia cells. Chest x-rays and special scans can reveal signs of the disease elsewhere in the body.
The most common treatments for leukemia are chemotherapy (kee-mo-THER-a-pee), radiation therapy, and/or bone marrow transplantation. In chemotherapy, patients take one or more anticancer drugs, often by mouth or intravenously (through a tube in one of the veins). In certain cases, doctors need to inject the drugs directly into the fluid that surrounds the brain and spinal cord. Chemotherapy can cause side effects, such as hair loss, nausea, fatigue, or easy bruising, depending on the drugs used. Most side effects go away gradually between treatments or after treatment stops.
In radiation therapy, doctors use a special machine to deliver high-energy rays that damage cancer cells and stop them from growing. They can direct the rays to one specific area of the body where leukemia cells have collected, such as the spleen, or to the whole body. Like chemotherapy, radiation therapy can cause temporary side effects, such as fatigue; hair loss; nausea; or red, dry, itchy skin.
In bone marrow transplantation, doctors give high doses of chemotherapy and radiation to destroy all of the patient's bone marrow. Doing so kills the cells that are the source of the cancer. They then give the patient healthy bone marrow from a donor whose tissue is similar. Ideally, the donor is an identical twin * or sibling. They also might give bone marrow that was removed from the patient earlier and specially treated to eliminate leukemia cells. A patient who has a bone marrow transplant usually stays in the hospital for several weeks. The risk of infection is high until the transplanted bone marrow begins to produce enough white blood cells.
Biological therapies have been more difficult to develop for acute leukemia, but several immunotherapy and targeted therapy drugs have been developed and subjected to testing. Some people with identified genetic abnormalities that make ALL resistant to standard therapy have been helped with drugs for treating CML. In 2016 a treatment method that alters the patient's own immune system infection-killing T cells so that they can recognize and fight leukemia cells was showing great promise. The immunotherapy was effective against both ALL and AML, but more testing is needed.
Living with leukemia can be difficult. Not only can the disease make someone feel sick, but many of the treatments can, too. Fortunately, treatments often make the disease go into remission. Patients who are in remission still need to see their doctors often for follow-up exams and tests. That way, if the leukemia comes back, medical professionals can detect it as early as possible.
Having leukemia can also be difficult emotionally. Patients are scared when they find out they have a form of cancer and worry about what the future may hold. Some people withdraw, get angry, or become depressed. With the support of family, friends, support groups, and health professionals, a spirit of realistic optimism can win out.
See also Cancer: Overview • Immune Deficiencies • Radiation Exposure
Morrison, Candis. Johns Hopkins Patients Guide to Leukemia. Burlington, MA: Jones & Bartlett Learning, 2010.
Mukherjee, Siddhartha. The Emperor of All Maladies: A Biography of Cancer. New York: Scribner, 2010.
MedlinePlus. “Acute Lymphocytic Leukemia.” U.S. National Library of Medicine. https://www.nlm.nih.gov/medlineplus/acutelymphocyticleukemia.html (accessed March 5, 2016).
American Cancer Society. 250 Williams St. NW, Atlanta, GA 30303. Toll-free: 800-227-2345. Website: http://www.cancer.org (accessed March 5, 2016).
Leukemia & Lymphoma Society. 1311 Mamaroneck Ave., Suite 310, White Plains, NY 10605. Telephone: 914-949-5213. Website: http://www.lls.org (accessed March 5, 2016).
National Bone Marrow Transplant Link. 20411 W. 12 Mile Rd., Suite 108, Southfield, MI 48076. Toll-free: 800-546-5268. Website: http://www.nbmtlink.org (accessed March 5, 2016).
National Cancer Institute. 9609 Medical Center Dr., Bldg. 9609, MSC 9760, Bethesda, MD 20892-9760. Toll-free: 800-422-6237. Website: http://www.cancer.gov (accessed March 5, 2016).
* risk factors are any factors that increase the chance of developing a disease.
* radiation is energy that is transmitted in the form of rays, waves, or particles. Only high-energy radiation, such as that found in x-rays and the sun's ultraviolet rays, has been proven to cause human cancer.
* radiation therapy is a treatment that uses high-energy radiation from x-rays and other sources to kill cancer cells and shrink cancerous growths.
* genes (JEENS) are chemical structures composed of deoxyribonucleic acid (DNA) that help determine a person's body structure, physical characteristics, and other traits. Inherited from a person's parents, genes are contained in the chromosomes found in the body's cells.
* lymph nodes (LIMF) are small, bean-shaped masses of tissue containing immune system cells that fight harmful microorganisms. Lymph nodes may swell during infections.
* liver is a large organ located beneath the ribs on the right side of the body. The liver performs numerous digestive and chemical functions essential for health.
* spleen is an organ in the upperleft part of the abdomen that stores and filters blood. As part of the immune system, the spleen also plays a role in fighting infection.
* herpes (HER-peez) is a viral infection that can produce painful, recurring skin blisters around the mouth or the genitals, and sometimes symptoms of infection elsewhere in the body.
* aspiration (as-puh-RAY-shun) is the sucking of fluid or other material out of the body, such as the removal of a sample of joint fluid through a needle inserted into the joint.
* identical twins are twins produced when a single egg from the mother is fertilized and divides to form two separate embryos of the same sex with nearly identical DNA.