Childhood Leukemia

By Peter Galvin, MD

Leukemia, a word that comes from Greek meaning “white blood,” is the most common form of cancer in children and adolescents. It starts in the bone marrow (the soft center part of bones) where all blood cells are produced. Once a leukemic cell develops, it multiplies quickly and soon overwhelms the marrow, thereby preventing the development of normal blood cells. Leukemic cells can spill out of the marrow and spread to other parts of the body, including the fluid that surrounds the brain and spinal cord (cerebrospinal fluid, or CSF) and other organs like the liver and kidneys. Unlike leukemia in adults, which in many cases has a known cause (exposure to ionizing radiation, chemicals [benzene and formaldehyde], or prior cancer chemotherapy), the cause of leukemia in children is usually unknown.

Leukemia cells are commonly large, immature, non-functional blood cells called blasts. In acute lymphoblastic leukemia (ALL), the most common form, the cells are immature, dysfunctional white blood cells (B-cells). In acute myeloid (or myeloblastic) leukemia (AML), they are other forms of white cells, red cells, or platelets. Each year in the U.S., there are about 3,000 children and adolescents diagnosed with ALL, and about 700 with AML. The symptoms of leukemia stem mainly from the fact that the marrow cannot produce enough normal blood cells plus the fact that the leukemic cells are dysfunctional. This means that the patient may be anemic, may bleed because of an inadequate number of platelets, or may have a compromised immune system. This leads to symptoms such as unexplained fevers, lethargy, shortness of breath, easy bruisability, and bone and joint pain.

The diagnosis of leukemia can often be made simply by examining a smear of the patient’s blood under a microscope, where the large blastic cells can be seen. Further testing is usually required and may involve a bone marrow aspirate and/or a lumber puncture to check for cancerous cells in the CSF. More specific tests such as immunophenotyping and cytogenetic testing may be needed to determine the type of leukemia and obtain information necessary to determine prognosis and treatment. Treatment depends on the age of the patient and the type of leukemia and is often adjusted based on the response to treatment. Treatment will usually include chemotherapy, radiation treatment, and often bone marrow transplant. Recent advances in treatment such as immunotherapy, which uses the patient’s own immune system to identify and kill leukemic cells, have greatly improved both the overall prognosis and long-term survival.

While a diagnosis of childhood leukemia is heart-wrenching for parents and families, the overall prognosis has greatly improved in the last decade or two. With current therapies, the five-year survival rate for ALL is now approximately 90%, and 68% for AML. Plus, should the child live five years cancer-free, today the likelihood of the cancer ever returning is about zero. For more information go to the American Cancer Society at:        www.cancer.org/cancer/types/leukemia-in-children/about.html

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