What is childhood leukemia?
Leukemia is a blood-borne type of malignancy that mostly affects extremities of ages; childhood, and adulthood. It’s the most common type of cancer among children which accounts for 1/3 of all childhood cancers. However, leukemia is rare in childhood and the outcome is generally good.
Leukemia is categorized traditionally as acute and chronic leukemia. Acute leukemia progress very rapidly and usually fatal if not treated on time. Conversely, chronic leukemia has a gradual onset and progression. However acute leukemia can be completely cured, whereas chronic leukemia is rarely curable.
Most of childhood leukemia are acute in type. Hence urgent and prompt management is needed. Acute childhood leukemia can either be acute lymphoblastic leukemia or acute myeloid leukemia. 90% of childhood leukemia are acute lymphoblastic in type. Acute myeloid leukemia has a higher occurrence among adults.
Uncontrolled cell proliferation and selective cell survival at the bone marrow brings out the picture of leukemia. Significant numbers of leukemic cells are released to blood while the leukemic cells remaining in the bone marrow erode and destroy the normal marrow. Leukemic proliferation can occur in any blood cell line. In acute lymphoblastic leukemia characteristically, proliferation occurs in T or B lymphocytes.
Causes of leukemia
Childhood leukemia occurs in an unpredictable manner. Exposure to radiation, Chemotherapy to previous cancers, viral infections like human T-lymphotropic virus (HTLV-1) and HIV virus, exposure to chemicals like benzene may be the triggering factors of leukemia. Genetic predisposition is rare except in congenital genetic diseases like down syndrome.
Symptoms of Childhood Leukemia
- Sudden, unexplained weight loss of more than 10% within 6 months or more than 5 % within a month
- Multiple lymph node enlargements
- Signs of anemia like pale palms, fatigue, dizziness
- Spontaneous bleeding
- Skin rashes and red spots on the skin
- Difficulty in breathing in leukemia involving the thymus
- Bone pains
- Frequent infections
- Night sweating
Effects of Childhood leukemia
Clinical effects of leukemia occur due to two main reasons.
1. Direct effects of leukemia
2. Due to the reduction of normal blood cells
Excessive cell proliferation depletes body protein and energy stores which manifests as sudden weight loss and extreme thinning. Tumor masses in bone marrow erode the bones which give rise to severe bone pains and bone fractures. The compression of lungs by enlarged lymphoid organs (thymus) produces chest pain and difficulty in breathing. Loss of normal blood cells leads to anemia, spontaneous bleeding, and frequent severe infections.
Investigations and diagnosis
Symptoms are non-specific and can occur due to many other diseases. Therefore, laboratory investigations have to be done to confirm, if there’s any suspicion of leukemia.
A full blood count is done as the 1st line screening investigation for the diagnosis of leukemia. Abnormally high cell counts, usually the white blood cells count, may raise the suspicion of childhood leukemia. However, most of the time it’s due to infections. Blood and bone marrow studies including immunohistochemistry, karyotyping, polymerase chain reaction and fluorescence in situ hybridization are done for the definitive diagnosis.
Treatment of Childhood Leukemia
Since most of the childhood leukemia are acute in type, aggressive treatment is necessary. Most of them respond to treatment. Management of childhood leukemia has 5 main phases.
1. Remission induction
2. Intensification/ Consolidation
3. CNS directed therapy
5. Definitive treatment
In the induction phase, the patient is treated for 6-8 weeks with chemotherapy to get the patient to remission (Blood being free of leukemic cells). Then the patient is aggressively treated with cytotoxic drugs to destroy any residual leukemic cells. This is called intensification. It may have one or two phases. Intra-thecal chemotherapy and systemic chemotherapy that penetrate the brain are given in the CNS phase to destroy leukemic cells in the brain or spinal code. Finally, the patient is given low-level chemotherapy for a longer period, usually 2-3 years, to prevent relapses of leukemia. In addition to the therapy, supportive care, high nutritious diet, love, and affection are also needed for a better outcome of the child.
Definitive treatment is the bone marrow transplant. But it’s not indicated following 1st remission except in severe forms of the disease. If the patient once again develops leukemia, bone marrow transplant is done following the 2nd remission.
Prognosis/ Survival in Childhood Leukemia
Survival of children with leukemia depends on the type of leukemia, genetic findings of the tumor cells and the time of diagnosis. Generally, childhood leukemia is considered to have a good outcome. In children, acute lymphoblastic leukemia has a significantly better outcome than acute myeloid leukemia. Among children with acute lymphoblastic leukemia, the prognosis depends on patient-specific factors and specific genetic mutations. Presence of Philadelphia chromosome, hypoploidy (less than 46 chromosomes), White blood cell count over 50 000 at the time of diagnosis, Failure of remission at the end of 4 weeks usually indicates a poor outcome.
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