Leukemia-Acute Lymphocytic Leukemia (ALL) – Adults

Acute Lymphocytic Leukemia (ALL) – Adults

Leukemia is a type of cancer that affects the blood and bone marrow. In acute lymphocytic leukemia (ALL), the cancer starts in immature white blood cells called lymphocytes. These cells are a critical part of the body’s immune system. ALL, also known as acute lymphoid or acute lymphoblastic leukemia, progresses rapidly, and treatment must begin soon after diagnosis.

ALL affects both children and adults, though it is most common in young children and individuals over 50 years of age. However, it can occur at any age.

Types of Lymphocytes:

1. B cells (B-lymphocytes): Produce antibodies to fight bacteria and infections.

2. T cells (T-lymphocytes): Help destroy infected cells and stimulate B cells to make antibodies.

3. Natural killer (NK) cells: Destroy virus-infected cells and certain cancer cells.

Around 85% of ALL cases involve B-cell subtypes, while T-cell subtypes account for 15%, and NK cell ALL is extremely rare.

What Happens in ALL?

ALL starts when immature lymphocytes (called lymphoblasts) begin to multiply uncontrollably in the bone marrow. This excessive production of lymphoblasts crowds out the normal production of other important blood cells:

• Red Blood Cells (RBCs): Carry oxygen throughout the body.

• Other White Blood Cells (WBCs): Help fight infections.

• Platelets: Help in blood clotting.

As a result, symptoms such as anemia, infections, and easy bruising or bleeding may occur. In some cases, lymphoblasts accumulate in the lymph nodes, causing swelling.

Unlike many cancers, ALL can spread to other parts of the body early, even before symptoms arise. However, this does not mean it is untreatable, and early treatment can often lead to remission.

Statistics

In India, around 48,419 cases of leukemia are diagnosed annually. Specific data for ALL is unavailable. In the United States, approximately 6,540 people are diagnosed with ALL each year.

Survival Rate

For adults over 20, the 5-year survival rate is 43%. For individuals under 20, the survival rate is significantly higher at 90%.

Risk Factors

The exact cause of ALL is unclear, but several factors increase the risk:

• Age: ALL is more common in children under 15 and adults over 50.

• Genetic conditions: Conditions such as Down syndrome, Ataxia telangiectasia, Li-Fraumeni syndrome, and Fanconi anemia increase the risk.

• Radiation exposure: High levels of radiation exposure can increase the risk of ALL.

• Viruses: Viruses like the Human T-cell leukemia virus (HTLV-1) and Epstein-Barr virus (EBV) may raise the risk.

Symptoms

Common symptoms of ALL include:

• Fatigue

• Weakness

• Easy bruising or bleeding

• Pale skin

• Tiny red spots on the skin (petechiae)

• Unexplained weight loss

• Fever

• Bone or joint pain

• Abdominal pain

• Shortness of breath

• Swollen lymph nodes

• Headaches

• Vision problems

• Nausea and vomiting

Diagnosis

1. Complete Blood Count (CBC): To check for abnormal levels of blood cells.

2. Bone Marrow Aspiration and Biopsy: A sample of liquid bone marrow or a solid core of bone is taken from the hip bone to check for cancer cells.

3. Flow Cytometry: A test that uses dyes to determine the leukemia subtype.

4. Karyotyping or Cytogenetics: Analyzes chromosomes to identify mutations, such as the Philadelphia chromosome.

5. Molecular Assays: Detects genetic mutations not visible through other tests.

6. Lumbar Puncture (Spinal Tap): A sample of cerebrospinal fluid (CSF) is taken to check for leukemia cells, as ALL can spread to the central nervous system.

7. Imaging Tests: CT scans, MRI, and PET scans may be used to detect the spread of leukemia.

Subtypes of ALL

ALL can be classified based on the type of lymphocytes involved:

• Precursor B-cell ALL

• Precursor T-cell ALL

• Burkitt-type ALL

• Philadelphia chromosome-positive ALL

Classification of ALL

Unlike other cancers, ALL does not form solid tumors and can spread throughout the body at diagnosis. Therefore, staging systems used for other cancers do not apply. Instead, ALL is classified as:

• Newly diagnosed: Abnormal lymphoblasts are present in the bone marrow.

• In remission: Treatment has reduced lymphoblasts in the bone marrow to less than 5%.

• Refractory: The disease does not respond to treatment.

• Recurrent or Relapsed ALL: The disease returns after remission.

Treatment Options

1. Chemotherapy:

Chemotherapy uses drugs to destroy cancer cells. It is the primary treatment for ALL and involves several phases:

• Remission Induction Therapy: The first treatment phase, given within 3 to 4 weeks of diagnosis, aims to destroy as many leukemia cells as possible. Drugs commonly used include:

• Daunorubicin

• Doxorubicin

• Vincristine

• Asparaginase

• Methotrexate (injected into the spinal fluid)

• Remission Consolidation or Intensification Therapy: After remission, this phase destroys any remaining cancer cells.

• Maintenance Therapy: Given as oral pills or injections for 2 to 3 years to prevent relapse.

• CNS Prophylaxis: Prevents leukemia from spreading to the brain or spinal cord by administering drugs directly into the CSF through a spinal tap.

2. Targeted Therapy:

Targeted therapy focuses on specific genes or proteins in cancer cells. In Philadelphia chromosome-positive ALL, targeted therapies like imatinib or dasatinib are used alongside chemotherapy.

Other targeted therapies for ALL include:

• Ponatinib

• Nelarabine

• Rituximab

• Blinatumomab

3. Radiation Therapy:

High-energy radiation is used to destroy cancer cells, especially if ALL has spread to the brain or spinal cord.

4. Bone Marrow/Stem Cell Transplantation:

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

Side Effects

Chemotherapy and targeted therapy can cause side effects such as:

• Hair loss

• Mouth sores

• Nausea and vomiting

• Fatigue

• Increased risk of infections

• Anemia

• Easy bruising or bleeding

Targeted therapies generally have fewer side effects, such as fluid retention and mild gastrointestinal issues. Radiation therapy can lead to hair loss, skin changes, and digestive problems.

Follow-Up Care

Regular follow-up tests, including physical exams, blood tests, and imaging, are necessary after treatment to monitor for recurrence and manage side effects.

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