Leukemia-Acute Lymphoblastic Leukemia (ALL) - Childhood

Acute Lymphoblastic Leukemia (ALL) - Childhood

Leukemia is a type of cancer that affects the blood and bone marrow. In acute lymphoblastic leukemia (ALL), the cancer begins in the white blood cells (WBCs) called lymphocytes, which are crucial to the body’s immune system. ALL is the most common type of childhood cancer.

What are Lymphocytes and Lymphoblasts?

Lymphocytes are produced in the bone marrow and are found in the blood, lymph nodes, spleen, and other parts of the immune system. Their role is to fight infections caused by bacteria and viruses. In children with ALL, immature lymphocytes called lymphoblasts continue to multiply without maturing into functional lymphocytes, leading to an overload of non-functional cells.

What is Acute Lymphoblastic Leukemia (ALL)?

When a child has ALL, the bone marrow is filled with immature lymphoblasts, preventing the production of normal red blood cells (RBCs), white blood cells (WBCs), and platelets. This leads to various symptoms:

• Fatigue: Caused by a lack of RBCs (anemia), leading to symptoms like tiredness, dizziness, pale skin, and rapid heartbeat.

• Easy bruising or bleeding: Due to low platelet counts, making it hard for blood to clot.

• Frequent infections: Because there are not enough healthy WBCs to fight germs.

Statistics

In India, about 48,419 cases of leukemia are diagnosed annually, but specific statistics for ALL are not available. ALL is the most common cancer in children. In the U.S., about 75% of leukemia cases in children under 20 are ALL, with most diagnoses occurring between ages 2 and 5.

Survival Rate

For children under 14, the 5-year survival rate for ALL is 92%. For those aged 15 to 19, the survival rate is 77%.

Risk Factors

While the exact cause of ALL in children is unknown, certain genetic disorders increase the risk. These include Down syndrome, ataxia-telangiectasia, and Bloom syndrome.

Symptoms

The early symptoms of ALL can resemble those of a viral infection, including:

• Frequent infections

• Persistent fever

• Constant fatigue

• Bone pain

• Swelling in the lymph nodes

• Pale skin

• Easy bruising or bleeding

• Shortness of breath

• Headaches

Diagnosis

1. Blood Tests (CBC): To detect abnormalities in WBC, RBC, and platelet levels.

2. Bone Marrow Aspiration and Biopsy: A needle is used to remove liquid bone marrow or a solid bone sample to check for leukemia cells.

3. Lumbar Puncture (Spinal Tap): A sample of cerebrospinal fluid (CSF) is taken to check for cancer cells.

Classification of ALL

Unlike other cancers, ALL is not staged in the same way. Factors that influence treatment decisions include:

• Age: Infants under 12 months and children over 10 years need more intensive treatment.

• WBC Count: If the count exceeds 50,000 per microliter, treatment is more aggressive.

• Immunophenotyping: This test identifies proteins produced by leukemia cells to tailor treatment.

• Genetic Abnormalities: Changes in chromosomes can influence the treatment approach.

• Response to Treatment: Early response in the first few weeks can predict overall treatment success.

ALL Treatment Terminology

• Untreated ALL: The leukemia has not been treated yet.

• ALL in Remission: After treatment, blood counts return to normal, and no leukemia cells are detected.

• Recurrent ALL: The leukemia has returned after treatment.

• Refractory ALL: The leukemia does not respond to treatment.

Treatment

1. Chemotherapy:

• This treatment uses drugs to destroy cancer cells. Chemotherapy for ALL involves several phases:

• Remission Induction Therapy: The initial phase aims to destroy as many leukemia cells as possible.

• CNS-Directed Therapy: To target and prevent cancer cells from spreading to the central nervous system.

• Consolidation Therapy: Given after remission to eliminate any remaining cancer cells.

• Continuation/Maintenance Therapy: May last 2 to 3 years to prevent the cancer from returning.

Common side effects include hair loss, fatigue, nausea, vomiting, and muscle weakness (if drugs like vincristine are used).

2. Radiation Therapy:

• High-energy radiation is used to kill cancer cells. It is not typically the primary treatment for ALL but is used when the cancer spreads to the brain, spinal cord, or other areas.

• Side effects include hair loss, fatigue, skin changes, and digestive issues.

3. Bone Marrow/Stem Cell Transplantation:

• This involves replacing damaged bone marrow with healthy hematopoietic stem cells. It is commonly used for recurrent or refractory ALL.

• There are two types of stem cell transplants:

• Autologous (AUTO): Using the patient’s own cells (not commonly used for ALL).

• Allogeneic (ALLO): Using cells from a donor, which is the more common method for ALL.

Follow-Up Care

After treatment, regular follow-up tests are necessary to monitor for recurrence and manage side effects. These include routine physical exams, blood tests, and imaging to ensure that the cancer has not returned. Follow-up care is crucial for long-term health.

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