What is Leukemia?

What is Leukemia?

Leukemia is a blood cancer that disrupts the production of normal blood cells in the bone marrow and blood-producing organs. This can lead to anemia and conditions affecting the lymphatic system. When cell DNA changes in the bone marrow, normal blood cells mutate and cannot function normally. Leukemia affects white blood cells, which fight infection in the body, causing the immune system to weaken.

Many forms of leukemia exist. Some diseases primarily affect children, while others are more common in older adults. Treatment depends on the type of leukemia, a person's age, and their overall health. Present-day therapies and treatment strategies can often help manage leukemia.

Stages of Leukemia


Unlike other forms of cancer, leukemia does not usually form into masses or tumors. Instead, it affects the production of healthy white, red, and platelet blood cells in the bone marrow, replacing them with an overabundance of abnormal blood cells.

Leukemia is classified in stages depending on blood count, not the size of a tumor. Each leukemia subtype is classified according to a distinct system. This is usually based on the type of white blood cell affected or the unique mutations in leukemia cells.

Unlike most cancers, leukemia is not generally staged, except for chronic lymphocytic leukemia, which uses the Rai system:

  • Stage 0: This stage is classified as having high levels of white blood cells, yet symptoms have not appeared
  • Stage 1: This stage includes high levels of white blood cells and enlarged lymph nodes
  • Stage 2: This stage is determined by high levels of white blood cells, anemia, and possibly enlarged lymph nodes
  • Stage 3: This stage shows high levels of white blood cells, anemia, enlarged lymph nodes, and enlarged liver and/or spleen
  • Stage 4: This stage is identified by high levels of white blood cells, low levels of platelets, anemia, enlarged lymph nodes, and an enlarged liver and spleen

Types of Leukemia

  • Acute myeloid leukemia (AML) is the most common type affecting adults' blood and bone marrow. If left untreated, acute myeloid leukemia progresses quickly.
  • Chronic lymphocytic leukemia (CLL) is slow-developing cancer that usually affects older adults. CLL involves white blood cells called B cells or B lymphocytes. White blood cells fight infection in the body; compromising these cells leads to frequent infections. Symptoms of chronic lymphocytic leukemia may not appear for many years. However, if symptoms do occur, they can include swollen lymph nodes, extreme fatigue, and easy bruising. Treatment may not be necessary but could include chemotherapy, targeted therapies, and immunotherapy.
  • Chronic myeloid leukemia (CML) is considered an uncommon, slow-moving cancer caused by a spontaneous mutation known as the Philadelphia chromosome. CML usually affects older adults. Symptoms of chronic myeloid leukemia include bleeding easily, being pale, tired, unexplained weight loss, abdominal fullness or bloating, and night sweats.
  • Acute lymphocytic leukemia (ALL) is the most common childhood form of leukemia. Errors develop in the DNA, causing immature white blood cells to form instead of mature, healthy blood cells. Possible symptoms of acute lymphocytic leukemia are enlarged lymph nodes, bruising easily, fever, bone pain, bleeding gums, and recurrent infections. ALL is treated with chemotherapy or targeted drugs which destroy the cancer cells.

Symptoms & Signs of Leukemia


Leukemia symptoms or signs may not be evident in the early stages. It may be years before noticeable symptoms appear. Chronic myeloid leukemia (CML) can go months or even years before symptoms show up, after which the leukemia cells will increase more rapidly.

Common chronic leukemia symptoms include:

  • Bleeding or bruising easily
  • Pale complexion
  • Extreme fatigue
  • Unexplained weight loss
  • Night sweats
  • Enlarged lymph nodes
  • Fever
  • Abdominal fullness or bloating


Acute lymphocytic leukemia (ALL) is a blood cancer that targets children more often than adults. Symptoms of acute lymphocytic leukemia include:

  • Enlarged lymph nodes
  • Bruising easily
  • Fever
  • Bone pain
  • Bleeding gums
  • Frequent infections


Common acute myeloid leukemia (AML) symptoms include:

  • Fatigue
  • Feeling dizzy
  • Headaches
  • Pale skin
  • Unusual frequent bleeding

Causes of Leukemia


Doctors do not know the exact cause of leukemia, but believe that a combination of genetic factors and environmental causes can trigger it. Those who develop leukemia show unusual chromosome or gene mutations. However, these changes alone may not cause leukemia. There is no known prevention for leukemia.
Factors that may contribute to the development of childhood leukemia include:

  • Having a sibling with leukemia
  • Exposure to radiation
  • Immune system suppression treatments (children with organ transplants)
  • Exposure to pesticides (during pregnancy or childhood)
  • Exposure to chemicals such as benzene (a common ingredient in cleaning fluids and plastics)
  • Having received chemotherapy is linked to a higher risk of developing leukemia

Risk Factors

Risk Factors

Though the exact causes of leukemia are not known, educated speculation has concluded that there are particular risk factors associated with leukemia:

  • Age - Over 50 years old
  • Exposure to hazardous chemicals
  • Family history
  • Gender - Males developing leukemia are slightly higher
  • Race - People of European descent have an increased risk of leukemia; those of Asian descent have the lowest risk



There are no absolute ways to prevent leukemia, but some actions can be taken to help reduce the likelihood of a person developing it:

  • Don't smoke
  • Maintain a healthy weight
  • Avoid exposure to harmful chemical
  • Make sure to see a doctor and report any unusual symptoms that you feel or observe

If you have signs or symptoms of leukemia that are causing you concern, make an appointment with your doctor. Don't wait.

Get Care

Trust NewYork-Presbyterian for Leukemia Care

At NewYork-Presbyterian, we’re here to support you and your loved ones from diagnosis to remission. Our team of medical professionals collaborates to ensure that leukemia is treated from every angle, ensuring a thorough treatment plan and a recovery process that’s easy as possible.