Leukemia -Acute Myeloid Leukemia (AML) – Childhood

Acute Myeloid Leukemia (AML) – Childhood

Acute Myeloid Leukemia (AML) is a type of cancer that affects the blood and bone marrow, where blood cells are produced. AML occurs when the DNA of immature myeloid cells, found in the bone marrow, is damaged. These abnormal cells, called myeloblasts or blasts, multiply uncontrollably, replacing healthy bone marrow and blood cells.

Bone Marrow

Bone marrow is the spongy tissue inside the bones, where blood cells are made. The main types of blood cells produced in the bone marrow are:

1. White blood cells (WBCs): Fight infections.

2. Red blood cells (RBCs): Carry oxygen throughout the body.

3. Platelets: Help with blood clotting.

About AML

AML starts when there is damage (mutation) to the DNA in myeloid cells, causing them to become abnormal. These damaged cells continue to grow and divide, eventually taking over the bone marrow and preventing the production of healthy blood cells. As a result, the body has fewer RBCs, WBCs, and platelets, leading to various symptoms and complications.

Statistics

Leukemia is the most common type of cancer in children, and AML is the second most common form of leukemia after Acute Lymphoblastic Leukemia (ALL). AML is typically found in children under the age of 2 and teenagers. In India, approximately 48,419 cases of leukemia are diagnosed annually, though specific data for AML is not available. In the United States, around 730 children under 20 are diagnosed with AML each year.

Survival Rate

For children under 15 years old, the 5-year survival rate for AML is 68%. For teenagers between 15 and 19 years, the survival rate remains the same at 68%.

Risk Factors

While the exact cause of AML is unknown, certain factors increase the risk of developing the disease:

• Genetic factors: Children with genetic conditions like Down syndrome are at a higher risk of developing AML.

• Age: AML is more common in children under 2 years of age.

Symptoms

Common symptoms of AML in children include:

• Fever

• Chills

• Bone and joint pain

• Swelling in lymph nodes

• Easy bruising or bleeding

• Pale skin

These symptoms may be caused by other conditions, so a diagnosis requires specific medical testing.

Diagnosis

1. Complete Blood Count (CBC): This blood test checks for abnormal levels of blood cells.

2. Bone Marrow Aspiration and Biopsy: Samples of bone marrow fluid and tissue are taken, usually from the hip bone, to check for cancer cells.

3. Immunohistochemistry: A test using special dyes to detect AML subtypes.

4. Karyotyping or Cytogenetics: Chromosome analysis to detect changes in the DNA.

5. Molecular Testing: Advanced tests to determine the genetic mutations and predict the effectiveness of targeted therapies.

Treatment

The main treatments for children with AML include chemotherapy and bone marrow or stem cell transplantation. Radiation therapy is rarely used, except in specific cases.

1. Chemotherapy

Chemotherapy is the primary treatment for AML. It uses powerful drugs to kill cancer cells. Chemotherapy is given in two phases:

• Induction Chemotherapy: The goal is to destroy as many leukemia cells as possible and bring the cancer into remission.

• Intensification Chemotherapy: After induction, this phase aims to kill any remaining cancer cells in the body.

Common side effects of chemotherapy include fatigue, low blood counts, infections, hair loss, nausea, vomiting, and loss of appetite. These side effects typically improve after treatment.

Special Subtypes of AML in Children:

• Children with Down Syndrome: Children under 4 years old with AML and Down syndrome respond well to lower doses of chemotherapy, with a 90% survival rate after 5 years.

• Acute Promyelocytic Leukemia (APL): This subtype is caused by changes in two genes (PML and RARA). Combining chemotherapy with all-trans retinoic acid (ATRA) and arsenic trioxide leads to a 90% success rate in these cases.

2. Bone Marrow or Stem Cell Transplantation

Stem cell transplantation is used when there is a high risk of relapse after treatment. It involves replacing the cancerous bone marrow with healthy stem cells to regenerate normal blood cells. The two types of stem cell transplants are:

• Autologous (AUTO): The patient’s own stem cells are used (not typically used in AML treatment).

• Allogeneic (ALLO): Stem cells are taken from a donor, usually a close match.

High doses of chemotherapy or radiation are used to destroy the cancer cells before the transplant.

3. Radiation Therapy

Radiation therapy uses high-energy radiation to kill cancer cells. External beam radiation therapy is the most common type. In AML, radiation is sometimes used to treat cancer that has spread to the brain or spinal cord.

Follow up

After AML treatment, regular follow-up appointments are crucial to monitor the child’s recovery and detect any signs of relapse. Follow-up care includes:

• Physical exams

• Blood tests

• Imaging tests to ensure the cancer has not returned

AML in children requires long-term monitoring, but many children successfully recover with the right treatment.

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