What is the Most Common Childhood Leukemia?

Unfairly affecting the littlest souls, acute lymphoblastic leukemia, or ALL, is treatable but it is a long process.

Definition

Leukemia is a common malignancy in children and adults that occurs when cells of the blood-forming bone marrow, or hematopoietic stem cells, grow uncontrolled.

Acute lymphoblastic leukemia, or ALL, is the most common cancer in children. It’s associated with too many immature white blood cells in the child’s blood and bone marrow. While it can occur in adults as well, the treatment is different when it occurs in children.

Symptoms and Signs

Common signs and symptoms include:

According to studies of pediatric cases, the following are also common:

  • Bone/joint pain, particularly in the spine and long bones
  • Enlarged liver or spleen
  • Enlarged lymph nodes

About 7 percent of children have involvement of the central nervous system at diagnosis.

Risk Factors

Risk factors for developing ALL include radiation exposure and several genetic syndromes. Household pesticide exposure in utero and during the first 3 years of life is also associated with increased risk of ALL.

Diagnosis

During the physical exam, your child’s doctor may detect enlarged lymph nodes, areas of bleeding or bruising, or possible signs of infection.  When the doctor palpates the child’s abdomen, an enlarged spleen or liver might be noted. Blood tests will be ordered and cell counts examined.

When results suggest leukemia, the doctor may refer you to a hematologist, a doctor who specializes in treating blood disorders, who may run more tests, including biopsy and analysis of the cells.

Classification of the type of ALL may depend on much more than appearance under the microscope these days, drawing on information related to the cancer's chromosomes and genes.

Staging and Evaluation

The application of the National Cancer Institute, or NCI, criteria results in those aged 1 to 10 years with initial white blood cell count less than 50,000/μL classified as "standard risk;" all infants, older children and those with higher numbers of white blood cells at the time of diagnosis are classified as high risk.

Several other systems are in use, however, to formulate a detailed picture of the level of risk from ALL.

  • Characteristics of the leukemia cells themselves are involved. For instance, which protein markers are expressed on the outside of cells, and whether they look like cells that would eventually become B lymphocytes or T lymphocytes. Approximately 80 percent of pediatric patients with ALL have B-precursor type, and this type used to be more favorable, but the T-cell type is catching up with differing treatment and more favorable outcomes.
  • Genetic abnormalities in the leukemic cells allow a molecular classification of risk.
  • In addition to the above features that are used to inform prognosis, the response to the initial therapy -- or lack thereof -- also sheds light on risk and prognosis.

Factors associated with higher-risk ALL include:

  • Age less than 1 year old or greater than 10 years old
  • Initial white blood cell count greater than 50,000/μL
  • Central nervous system involvement
  • Testicular involvement
  • Unfavorable genetics
  • Suboptimal response to initial therapy

Treatment

Treatment of childhood ALL relies on grouping of individuals into different risk categories based on features that have been shown to affect prognosis. Those with favorable features can be treated with less toxic regimens, while more aggressive regimens may be reserved for those with more high-risk disease.

There are 4 major components of treatment of newly diagnosed ALL. The earliest treatments are done in the hospital setting, while maintenance therapy can be given with oral medication as an outpatient. Due to the potential side effects of treating the central nervous system, this phase of treatment has been on the decline at some institutions.

1. Remission induction is the first block of chemotherapy, lasting 4 to 6 weeks.

-- Agents used during induction include vincristine, corticosteroids, and asparaginase, with most regimens adding an anthracycline (usually doxorubicin or daunorubicin)

2. Consolidation attempts to get rid of disease that remains after a complete remission is obtained. It lasts about 6 to 9 months, with longer and more intense regimens for higher-risk disease.

-- Agents may include some not used in the initial remission induction, such as mercaptopurine, thioguanine, methotrexate, cyclophosphamide, etoposide, and cytarabine.

3. Maintenance chemotherapy has been shown to lower the risk of relapse. It usually lasts at least 2 years.

-- Maintenance treatment is usually with methotrexate and mercaptopurine

4. +/- Treatment directed at the central nervous system, or CNS

-- The goal is getting rid of any disease in the CNS, and chemotherapy may be given directly into the space which houses the brain and spinal cord, or chemotherapy that is able to penetrate the blood-brain barrier may be chosen, or radiation may be delivered to the head.

-- Sometimes this is reserved for those at the highest risk for relapse; some institutions don’t use it at all.

Prognosis

ALL has an overall survival of approximately 80 percent, with certain subsets experiencing greater than 98 percent cure rate, according to the February 2015 review published in “Pediatric Clinics of North America.”

Sources

Cooper SL, Brown PA. Treatment of Pediatric Acute Lymphoblastic Leukemia. Pediatr Clin North Am. 2015;62(1):61-73.

Gaynon PS, Angiolillo AL, Carroll WL, et al. Long-term results of the children’s cancer group studies for childhood acute lymphoblastic leukemia 1983–2002: a Children’s Oncology Group Report. Leukemia. 2010;24(2):285–97.

Davis AS, Viera AJ, Mead MD. Leukemia: an overview for primary care. Am Fam Physician. 2014 May 1;89(9):731-8.

Sinigaglia R, Gigante C, Bisinella, et al. Musculoskeletal manifestations in pediatric acute leukemia. J Pediatr Orthop. 2008;28(1):20–28.

Ma SK, Chan GC, Ha SY, et al. Clinical presentation, hematologic features and treatment outcome of childhood acute lymphoblastic leukemia: a review of 73 cases in Hong Kong. Hematol Oncol. 1997;15(3):141–149.

Rogalsky RJ, Black GB, Reed MH. Orthopaedic manifestations of leukemia in children. J Bone Joint Surg Am. 1986;68(4):494–501.

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