This is the most common form of childhood cancer, accounting for one-third of all cancers diagnosed in children each year. In leukemia—as in all cancers—one type of cell grows out of control. Leukemia can occur at any time during childhood, but most cases develop between the ages of three and five.
Although any cancer diagnosis is serious, leukemia is now one of the most successfully treated forms of the disease. As with other types of cancer, chances of a cure are greatest when the disease is diagnosed and treated in its early stages. Thanks to great advances in the management of childhood leukemia over the past 25 years, the majority of affected children will achieve long-term remissions, with an increasing number apparently cured.
HOW DOES LEUKEMIA DEVELOP?
All blood cells originate in the bone marrow, the soft substance in the interior channel that runs through the long bones. Leukemia develops when some trigger—as yet unidentified—causes one of the precursors of white cells to mutate in its early development within the bone marrow. The cells proliferate rapidly and uncontrollably, overcrowding the bone marrow and preventing production of adequate amounts of normally functioning blood cells. Via the bloodstream, the abnormal cells spread throughout the body.
These abnormal white blood cells crowd out the normal blood cells in the marrow, leading to anemia and impaired blood clotting. In addition, the lack of normal white blood cells opens the door to severe infections.
The exact cause of leukemia is unknown. Children with certain genetic disorders (such as Down's syndrome) seem to have an inborn predisposition to developing the disease. Since most children with these disorders do not develop leukemia, it seems likely that a second factor (such as exposure to some environmental toxin) is required to initiate the disease process.
WHEN SHOULD I SUSPECT THAT MY CHILD HAS LEUKEMIA?
Possible symptoms include:
• Fatigue, pallor, weakness, malaise, increased heart rate and irritability
• Frequent fever and infections (results of insufficient white blood cells)
• Increased bruising, nosebleeds and gum bleeding (results of insufficient platelets)
• Limping (a result of bone soreness)
• Enlargement of the spleen, liver, lymph nodes, thymus gland and kidneys (a direct result of proliferating white blood cells)
WHAT ARE THE DIFFERENT TYPES OF LEUKEMIA?
Leukemia is classified according to the speed at which it progresses (acute or chronic) and by the type of white blood cell it affects. Acute forms account for 97 percent of childhood leukemias. They are characterized by a quick onset and rapid progression; in as little as two months, abnormal white cells may have crowded out almost all normal blood cells. The less common chronic leukemias develop more slowly, over two years or more.
The most common leukemia affecting children is acute lymphocytic leukemia (ALL), marked by abnormal proliferation of a type of white blood cell known as lymphocytes. This form affects about 80 to 85 percent of children with the disease. Acute granulocytic leukemia and acute monocytic leukemia, much less common, are often referred to collectively as acute nonlymphocytic leukemia.
WHAT TREATMENTS ARE AVAILABLE?
The goal of leukemia therapy is to eliminate all the abnormal white blood cells, making way for new, healthy cells to develop, multiply and resume normal functioning. Chemotherapy is usually the first choice. A number of different drug combinations have been developed to kill abnormal bone marrow cells; the physician's choice depends on which type of leukemia the child has.
During the initial phase of treatment, the child also receives blood transfusions and antibiotics. Chemotherapy is usually continued until all detectable abnormal cells in the bone marrow have been destroyed, usually by four to six weeks. To maintain the remission, the child will receive a less intense course of chemotherapy at regular intervals, usually for two to three years.
A child whose leukemia has gone into remission (meaning that all detectable abnormal cells have disappeared) must be watched carefully for signs of relapse, particularly within the first year after the drugs are stopped.
OTHER TREATMENTS
Bone marrow transplants have become increasingly important in the therapy of childhood leukemia. This procedure, performed after intensive radiation or chemotherapy to destroy the unhealthy marrow, involves intravenous infusions of marrow cells from a donor who is immunologically compatible—ideally, a sibling. Bone marrow transplantation usually is recommended for children with newly diagnosed ALL in remission and for children with ALL who have experienced one or more relapses.
Bone marrow transplantation is lengthy, risky and expensive. Parents whose children are undergoing the treatment may need extra emotional support from their extended families, as well as from mental health professionals.
COPING WITH LEUKEMIA
The responsibility of caring for a child with leukemia can take a toll on parents. Here are some suggestions to help you cope:
• Arrange for help at home, including babysitters.
• Do not isolate yourself socially, but avoid people who are not supportive.
• Learn about community resources, such as a support group with other parents of children with cancer.
• If necessary, seek professional counseling.
GETTING HELP
Call your doctor if your child develops any signs and symptoms of leukemia, which can appear quite suddenly; be particularly alert to unusual bruising, unexplained pain and limping, frequent nosebleeds and bleeding gums.
