Definition

Leukemia is a cancer of the blood cells. Three main types of blood cells are:

• White blood cells (WBC), also called lymphocytes—help the immune system
• Red blood cells (RBC)—carry oxygen
• Platelets—help the blood clot at injury sites

White blood cells are most often involved in leukemia.

The most common types of leukemia are:

• Acute lymphocytic leukemia (ALL)
• Acute myelogenous leukemia (AML)
• Chronic lymphocytic leukemia (CLL)
• Chronic myelogenous leukemia (CML)

White Blood Cells Leukemia cells outnumber healthy white blood cells and gather in spleen and lymph nodes. Copyright © Nucleus Medical Media, Inc.

Causes

Leukemia starts in the bone marrow where blood cells are made. It happens when certain blood cells divide without control or order. The abnormal cells crowd out the healthy blood cells. This causes many of the symptoms.

The cause of leukemia is not clear. It is likely a combination of genes and environment.

Risk Factors

AML and CML are most common in adults over 60 years. ALL is most common in children.

Other things that may raise the risk of leukemia are:

• A history of radiation treatment or chemotherapy
• Exposure to certain chemicals, such as benzene
• Smoking—linked to AML
• Some genetic diseases, such as Down syndrome
• Myelodysplastic syndrome —a blood disease, which raises the risk for AML

Symptoms

Symptoms of leukemia may be:

• Feeling weak or tired
• Fever or night sweats
• Weight loss without trying
• Easy bleeding and bruising
• Problems breathing
• Pale skin, or tiny red spots under the skin
• Painless lumps in the neck, underarms, belly, or groin
• Pain in the bones or joints, or discomfort in the belly

Diagnosis

The doctor will ask about your symptoms and health history. A physical exam will be done. The doctor will check for swelling of the liver, spleen, or lymph nodes in the armpits, groin, and neck.

Tests may include:

• Blood tests—to look for leukemia cells in blood
• Bone marrow aspiration and biopsy —a sample of bone marrow is taken and tested for cancer cells

If cancer cells are found, other tests may be done. These tests check if the cancer has spread. They may include:

• Lumbar puncture —tests fluid around the brain and spinal cord for cancer cells
• Imaging tests, such as:
  • Chest x-rays
  • CT scan
  • MRI scan
  • Ultrasound
  • PET/CT scan

Treatment

The goal for acute leukemia is to destroy cancer cells and return blood and bone marrow to normal. Chronic leukemia is rarely curable. Treatment focuses on slowing the disease.

A number of treatments may be used. It depends on the person's age, health, and the type and stage of the disease. Options may include:

• Targeted therapy—drugs that reduce the number of cancer cells in the blood and bone marrow
• Chemotherapy by mouth, injection, or IV—to kill cancer cells
• Immunotherapy—drugs to help the body fight cancer cells
• Supportive therapy, such as:
  • Drugs to prevent side effects
  • Antibiotics and anti-viral drugs—to prevent infections
  • Blood transfusions—to replace low numbers of blood cells
• External or internal radiation therapy—to kill cancer cells, often before a bone marrow transplant
• Bone marrow transplant—an injection of healthy bone marrow, to make healthy blood cells
• Splenectomy—surgery to remove the spleen, if it is causing problems

Prevention

The risk of leukemia may be reduced by:

• Not smoking
• Avoiding harmful chemicals, such as benzene
• Avoiding exposure to high levels of radiation, when possible