Leukemia is a rare cancer of the blood that is sometimes easy to confuse with other more common conditions in children — especially if they are very young. But it’s comforting to know that treatment success rates are very high.
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Pediatric oncologist Ilia Buhtoiarov, MD, discusses what forms this disease takes and how doctors treat it.
What are the different types of leukemia in children?
There are three main types of childhood leukemia.
- Acute lymphoblastic leukemia. Also known as ALL, this type may occur any time before the age of 21. It makes up about 75% of all childhood leukemia cases. Doctors diagnose it more than twice as often in children under age 15 and at even higher rates among very young children.“The most active time for leukemia is age 2 to 3,” Dr. Buhtoiarov says. “The frequency is four times higher than in any other age group.” This amounts to about 90 cases per million children.
- Acute myelogenous leukemia (AML). This type makes up about 20 percent of childhood leukemia cases. Similar to acute lymphoblastic leukemia, it happens more commonly in younger children. The highest incidence is before age 2. However, children with Down Syndrome may be born with the cells looking like myeloid blasts, a type of immature white blood cells. This condition is called Transient Myeloproliferative Disorder (TMD) or Transient Abnormal Myelopoiesis (TAM). It occurs in 5-10% of children with DS, and in most cases regress even without treatment within the first 3 to 4 months of life. About 20% of children with TMD will eventually develop AML, usually in the first 3 years of life.
- Chronic myelogenous leukemia (CML). This slowly progressing type occurs only very rarely in children.
What are the risk factors for childhood leukemia?
There are several features of ALL that involve gender, ethnicity and genetics:
- Girls have a higher risk before the age of 1; after that age, risk is higher for boys.
- Hispanic children have the highest rate of leukemia; the second highest rate is among Caucasian Americans. The group with the third highest risk is black Americans, which includes those from the Caribbean.
- Risk increases for children with radiation exposure in utero.
- Some genetic conditions, such as bone marrow failure syndromes, increase risk. The commonest genetic predisposition syndromes are Down Syndrome, Neurofibromatosis type 1, Bloom Syndrome, Fanconi Anemia, Li-Fraumeni syndrome and Ataxia Telangiectasia.
- A child whose identical twin has leukemia is almost certain to get it, typically within the first few years of the first twin’s diagnosis, especially if the first twin developed leukemia within the first year of life. The likelihood of leukemia in non-identical twins is lower than in identical twins and seems to correlate with the age of leukemia in the first twin; it is still higher than in general population or among siblings.
What are the symptoms of childhood leukemia?
Childhood leukemia is often easy to miss because there are a variety of symptoms that show up in different ways.
“I wish leukemia had a unique presentation so we would know right away when we look at a child whether he has it,” Dr. Buhtoiarov says.
“But often, kids just aren’t feeling well and end up visiting an emergency room or family doctor. Then, one day, the fever doesn’t go away or the pain doesn’t resolve, and it is found by default when they do blood work.”
Symptoms to watch for may include:
- Unusual fatigue.
- Pallor (pale appearance).
- Unexplained, frequent bruising, often in the chest and back.
- Fever (not from an infection).
- Pain in the legs or stomach.
- Loss of appetite.
- Enlarged lymph nodes, liver or spleen.
What are the treatment options?
Chemotherapy. For most children, doctors treat leukemia with chemotherapy. This treatment typically lasts about 2 1/2 years for girls, and about 3 1/2 years for boys. Doctors treat boys for a longer time because there is a likelihood of recurrence if treatment falls short, Dr. Buhtoiarov says.
If the child does not go into remission or the leukemia comes back, doctors may increase the treatment intensity.
Stem cell transplantation. Doctors may consider this treatment for children who:
- Are under the age of 1 or over age 10.
- Have an extremely high amount of leukemia in the blood at the time of diagnosis.
- Where found to have genetic mutations in the leukemia cells that render them insensitive to common chemotherapy agents.
Immunotherapy. This has revolutionized the field of pediatric oncology. Immunotherapy includes different treatment approaches that “educate” a patient’s own immune system to recognize and kill leukemia cells
Fortunately, the success rate for leukemia treatment is high: There is about an 85% chance a child will go into remission, Dr. Buhtoiarov says. Children are “cured” if they are cancer-free for four years after treatment, he says.