Leukemia

Leukemia
Synonyms	Leukaemia
Pronounce
Field	Hematology and oncology
Symptoms	Bleeding, bruising, fatigue, fever, increased risk of infections
Complications
Onset	All ages, most common in 60s and 70s. It is the most common malignant cancer in children, but the cure rates are also higher for them.
Duration
Types	N/A
Causes	Inherited and environmental factors
Risks	Smoking, family history, ionizing radiation, some chemicals such as trichloroethylene, prior chemotherapy, Down syndrome.
Diagnosis	Blood tests, bone marrow biopsy
Differential diagnosis
Prevention
Treatment	Chemotherapy, radiation therapy, targeted therapy, bone marrow transplant, supportive care
Medication
Prognosis	Five-year survival rate 67% (U.S.)
Frequency	2.3 million (2015)
Deaths	353,500 (2015)

Blood cells (normal and leukemia)

Symptoms of leukemia

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Leukemia (aml)

Acute Myeloid Leukemia (M2 type)

Cytology of acute promyelocytic leukemia, annotated

Rudolf Virchow

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Leukemia SAG

Leukemia world map

A type of blood cancer affecting white blood cells and bone marrow.

Leukemia, also spelled leukaemia, is a type of cancer that affects the white blood cells and the bone marrow. It is characterized by the abnormal production of leukocytes, leading to a disruption in the balance of blood cell production. The excessive number of defective white blood cells interferes with the normal function of the immune system, making individuals more susceptible to infection, anemia, and bleeding disorders.

Leukemia belongs to a broader category of hematological neoplasms, also known as blood cancers. Without appropriate treatment, leukemia can be fatal within weeks, months, or years, depending on its type and progression.

Globally, leukemia affects both children and adults, though the majority of cases occur in adults. It is estimated that 90% of all leukemia cases are diagnosed in individuals over the age of 20.

Types of Leukemia

Leukemia is classified based on its progression rate and the type of blood cell affected. The two primary classifications are:

• Acute leukemia – Progresses rapidly and requires immediate treatment. It primarily affects immature blood cells (blasts), which are unable to function properly.
• Chronic leukemia – Progresses slowly and may not present symptoms for years. It allows the production of some functional white blood cells, though they remain defective.

Additionally, leukemia affects two main types of white blood cells:

• Lymphoid cells – Develop into lymphocytes, which are crucial for immune function.
• Myeloid cells – Give rise to granulocytes, monocytes, red blood cells, and platelets.

Based on these classifications, the four major types of leukemia are:

1. Acute Lymphocytic Leukemia (ALL)

• The most common type of leukemia in children, but can also affect adults.
• Rapid onset with symptoms such as fatigue, fever, bleeding, and infections.
• Can spread to the brain, spinal cord, and other organs if untreated.

2. Chronic Lymphocytic Leukemia (CLL)

• Typically affects older adults over the age of 55.
• May remain asymptomatic for years before showing signs such as swollen lymph nodes and fatigue.
• Often discovered incidentally during routine blood tests.

3. Acute Myelogenous Leukemia (AML)

• More common in adults but can occur in children.
• Characterized by the rapid growth of myeloid cells, leading to symptoms like bruising, infections, and weight loss.
• Requires aggressive treatment, often involving chemotherapy and stem cell transplants.

4. Chronic Myelogenous Leukemia (CML)

• Primarily seen in middle-aged and older adults.
• Has two phases: a slow-growing chronic phase followed by a rapidly progressing phase (blast crisis).
• Strongly associated with the Philadelphia chromosome (BCR-ABL gene mutation).

Causes and Risk Factors

The exact cause of leukemia is unknown, but several genetic and environmental factors contribute to its development:

Genetic Factors

• Chromosomal abnormalities, such as the Philadelphia chromosome (linked to CML).
• Inherited genetic disorders, including Fanconi anemia and Down syndrome.
• Family history – A close relative with leukemia slightly increases the risk.

Environmental Factors

• Exposure to ionizing radiation, such as nuclear fallout or high-dose X-rays.
• Prolonged exposure to benzene, a chemical found in industrial settings and cigarette smoke.
• Previous chemotherapy or radiation therapy, which can damage bone marrow cells.
• Exposure to certain viruses, including:
• Human immunodeficiency virus (HIV)
• Human T-lymphotropic virus (HTLV-1)

Symptoms of Leukemia

Leukemia symptoms vary depending on the type but commonly include:

• Fatigue and weakness – Due to anemia from low red blood cell count.
• Frequent infections – Resulting from abnormal white blood cells.
• Easy bruising and bleeding – Caused by reduced platelet count (thrombocytopenia).
• Swollen lymph nodes, liver, or spleen – Especially in CLL and ALL.
• Bone pain and joint discomfort – Due to leukemia cells accumulating in the bone marrow.
• Unexplained weight loss and fever – Common in acute leukemia.

Diagnosis

Leukemia is diagnosed using a combination of laboratory tests and imaging techniques, including:

• Complete blood count (CBC) – Checks for abnormal white blood cell levels.
• Peripheral blood smear – Examines the shape and structure of blood cells.
• Bone marrow biopsy – Confirms the presence of leukemia cells in the bone marrow.
• Cytogenetic analysis – Identifies specific chromosomal mutations, such as the Philadelphia chromosome.
• Lumbar puncture (spinal tap) – Determines if leukemia has spread to the central nervous system.

Treatment of Leukemia

Treatment depends on the type and stage of leukemia but often includes:

1. Chemotherapy

• The most common treatment, using powerful drugs to kill cancer cells.
• Administered orally, intravenously, or directly into the cerebrospinal fluid.

2. Radiation Therapy

• Uses high-energy X-rays to target leukemia cells.
• Often combined with chemotherapy for aggressive forms like ALL and AML.

3. Targeted Therapy

• Drugs designed to block specific cancer cell pathways.
• Examples include imatinib (Gleevec) for CML (targets the BCR-ABL protein).

4. Immunotherapy

• Enhances the body’s immune system to fight leukemia.
• Includes CAR-T cell therapy, which reprograms T-cells to attack leukemia cells.

5. Bone Marrow or Stem Cell Transplant

• Used in severe cases or after chemotherapy failure.
• Replaces diseased bone marrow with healthy donor stem cells.

Prognosis

The prognosis for leukemia varies significantly:

• Acute leukemia (ALL & AML) has a rapid progression but can be curable with early treatment.
• Chronic leukemia (CLL & CML) progresses slowly and may not require immediate treatment.
• Survival rates depend on age, overall health, and response to treatment:
• ALL – ~90% survival rate in children, lower in adults.
• AML – ~30-40% survival rate in adults.
• CLL – Can be managed for decades with modern therapies.
• CML – With targeted therapy, life expectancy approaches normal levels.

Prevention

Since leukemia has no definitive cause, preventing it is difficult. However, certain steps may reduce risk:

• Avoid exposure to carcinogens like benzene and radiation.
• Quit smoking, as tobacco increases the risk of blood cancers.
• Maintain a healthy lifestyle, including a balanced diet and exercise.
• Limit exposure to pesticides and industrial chemicals.
• Regular health check-ups for individuals with a family history of leukemia.

See Also

• Hematological neoplasms
• Lymphoma
• Multiple myeloma
• Bone marrow transplant
• Cancer treatment

External Links

• American Cancer Society – Leukemia
• Leukemia & Lymphoma Society

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