Leukemias – Causes, Signs and symptoms


Also called: Acute Leukemias, Chronic Leukemias

Reviewed By:
Mark Oren, M.D., FACP


Leukemias are cancers of the body’s blood-forming cells. They affect the body’s blood making system, including bone marrow and the lymphatic system.

Bone marrow is the soft, inner component of bones. All forms of blood cells are produced in the bone marrow including: 

  • White blood cells (fight infection)

  • Red blood cells (carry oxygen to tissues all over the body)

  • Platelets (help develop blood clots and control bleeding)

In patients with leukemia, the bone marrow manufactures a large number of abnormal white blood cells. Over time they begin to increase, crowding out normal white blood cells, red blood cells and platelets. This results in anemia, bleeding disorders and a decreased ability to fight off infection.

Leukemia develops in the bone marrow but typically spreads quickly into the blood. Eventually it spreads further into the lymph nodes, the liver, the covering of the spinal cord and brain, spinal fluid, the spleen and other organs. Without successful treatment, the disease is usually fatal.

There are many types and subtypes of leukemia. Most forms of leukemia can be classified into four main types. These include:

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

In addition to the four main types, there are also a number of rare types of leukemia.

The exact cause of leukemia has not been identified. Researchers have gained a greater understanding of how specific changes in DNA can cause cells to develop into leukemia. A number of risk factors have been identified, including smoking and exposure to high levels of radiation and certain chemicals. 

Symptoms of leukemia vary depending on the exact type of the disease and where it has spread in the body. In chronic leukemia, the symptoms may not appear for a long time. In acute leukemia, the symptoms usually develop quickly and rapidly become more severe.

The most common symptoms include fatigue, weakness and weight loss.

Leukemia may be first diagnosed by routine blood tests. However, additional tests that may be necessary include bone marrow tests, biopsy and lumbar puncture. The treatment for leukemia depends upon the type and severity of the disease. It may include chemotherapy, radiation therapy, biological therapy and bone marrow transplantation. Leukemia patients usually receive a combination of these therapies.

The American Cancer Society (ACS) estimates that there will be more than 44,000 new cases of leukemia diagnosed in the United States in 2007. The disease develops 10 times more often in adults than in children and is more common in men than women. The ACS estimates there will be slightly more cases of acute forms of leukemia than chronic leukemias.

Survival rates vary by type of leukemia. In 2007, almost 22,000 deaths will occur from leukemia, according to the ACS. Five-year survival rates vary from 20 percent for people with AML to 74 percent for patients with CLL.

About leukemias

Leukemia is cancer of the body’s blood-forming cells. It affects the body’s blood-making system, including bone marrow and the lymphatic system. Although it is often thought of as a children’s disease, it affects about 10 times as many adults as children. The disease also occurs more often in males than in females.

Bone marrow is the soft, inner component of bones. It is composed of blood-forming cells, fat cells, and tissues that support the growth of blood cells. All forms of blood cells are produced in the bone marrow from a mother cell called the stem cell. Blood cells produced in the bone marrow include:

  • White blood cells (cells that fight infection)

  • Red blood cells (cells that carry oxygen to, and carbon dioxide from, the body’s cells)

  • Platelets (cells that help develop blood clots and control bleeding)

Leukemia develops from bone marrow cells. In patients with leukemia, the bone marrow manufactures a large number of abnormal white blood cells. These cells are unable to defend the body from disease because they are defective. As the disease progresses the abnormal cells build up, crowding out normal white blood cells, red blood cells and platelets. Production of normal white blood cells is affected, and the body’s ability to fight infection is impaired. In addition, the decrease in production of red blood cells and platelets results in anemia and bleeding disorders.  

The disorder develops in the bone marrow but typically spreads quickly into the blood. Eventually it can spread into the lymph nodes, the liver, the covering of the spinal cord and brain, spinal fluid, the spleen and other organs.

The lymph nodes are small bean-shaped glands located in various parts of the body. The spleen is an organ that is located near the stomach. The spleen and lymph nodes are components of the lymphatic system, a network of organs, nodes and vessels. The lymphatic system removes lymph (fluid containing white blood cells, plasma and other substances) from tissues and returns it to the bloodstream. It is a major component of the immune system and defends the body from infections and disease.

In 2007, the American Cancer Society (ACS) estimates there will be more than 44,000 new cases of leukemia diagnosed in the United States. Although leukemia is often considered a childhood disease, it is actually 10 times more common in adults. In children, acute lymphocytic leukemia (ALL) accounts for the majority of the cases. In adults, acute myeloid leukemia (AML) and chronic lymphocytic leukemia (CLL) are the most common types of the disease. Certain forms of leukemia, such as CLL have decreased over the past 15 years while others (AML) have increased. Overall, death rates from leukemia in both males and females have decreased by about 0.6 percent since 1991.

Types and differences of leukemias

There are many types and subtypes of leukemia. In general, the disease is first classified according to how quickly it progresses. The second classification is based on the type of white blood cell from which the leukemia develops. The abnormal cells may be considered mature or immature depending on the cell type. Leukemia can develop in two forms of blood cells, lymphocytes and myeloid cells, and at two different rates of progression: acute and chronic.

The main terms used to describe leukemia include:

  • Acute. Acute leukemias are leukemias in which the cancer cells develop from early cells known as blast cells. The cells grow quickly but they fail to mature properly. This form grows rapidly because the cells divide often and continue to divide longer than normal blast cells. Although the white blood cell count is frequently high in these forms of leukemia, it can also be normal or low. Most cases of leukemia in children are acute, requiring aggressive and immediate treatment.

  • Chronic. Chronic leukemias are leukemias in which the cancer cells arise from more mature cells, but the cells are not entirely normal. The cells live abnormally long and begin to increase. As a result, a patient’s white blood cell count is almost always high at diagnosis. These forms of leukemia are usually slow-growing.

  • Lymphocytic. Leukemias of this type develop from lymphoblasts or lymphocytes in the bone marrow, which form lymphatic tissue. A main component of the immune system, lymphatic tissue is found throughout the body, and includes the lymph nodes and vessels, spleen and tonsils.

  • Myelogenous. Also known as myeloid or myelocytic leukemias, leukemias of this type develop from myeloid cells. The myeloid cells include cells that eventually develop into red blood cells, white blood cells and platelet-producing cells.

By examining these factors, most forms of leukemia can be classified into four main types. These include:

  • Acute lymphocytic leukemia (ALL)
    • Also known as acute lymphoblastic leukemia, the earliest lymphocyte cell

    • According to the American Cancer Society (ACS), ALL will account for about 5,200 new cases of leukemia in 2007

    • Two-thirds of all cases of ALL occur in children

    • Typically occurs between ages 3 and 6

    • Most common leukemia in children

    • Treatment is primarily chemotherapy, focusing on brain and spinal cord, where it commonly spreads

    • Several types of ALL, each with a different cure rate

    • Prognosis is greatly affected by age

  • Acute myeloid leukemia (AML)
    • Also known as acute myelogenous leukemia

    • According to the ACS, AML will account for approximately 13,410 new cases of leukemia in 2007

    • Roughly 90 percent of AML cases occur in adults

    • Based on the appearance of the cells, AML is divided into a variety of subtypes known as M1 – M7

    • Chemotherapy is the main treatment method for most subtypes

    • Prognosis depends on the subtype of the disease

  • Chronic lymphocytic leukemia (CLL)
    • Involves mature-looking lymphocytes

    • Occurs mainly in older adults, with the average age in the 60s

    • According to the ACS, CLL will account for approximately 15,340 new cases of leukemia in 2007

    • Main treatment method is chemotherapy and/or biological therapy

  • Chronic myelogenous leukemia (CML)
    • Also known as chronic myeloid leukemia

    • Usually occurs in middle-aged patients, with the average age in the 50s

    • Involves myelocytic cells

    • According to the ACS, CML will account for approximately 4,500 new cases of leukemia in 2007

    • Treatment methods include the drugs imatinib mesylate, interferon-alpha and chemotherapy

In addition to the four main types of leukemia, there are also a number of rare types. Rare leukemias, including hairy cell leukemia, account for almost 4,700 new cases of leukemia each year.

Studies have shown the best predictor for recovery outcome of leukemia may be based on the abnormality of the chromosome rather than the actual leukemia subtype. For this reason, cytologic studies may be conducted to determine the chromosome damage in addition to the type.

Potential causes and risk factors of leukemia

The exact cause of leukemia has not been identified. Researchers, however, have gained a greater understanding of how specific changes in DNA can cause bone marrow stem cells to develop into leukemia.

Some forms of cancer are caused by DNA mutations that “turn on” oncogenes (genes that speed up cell division) or “turn off” tumor suppressor genes (genes that slow down cell division or cause cells to die at the right time). In people with leukemia, these mutations are normally acquired after birth. The mutations may occur from exposure to radiation or cancer-causing chemicals, but many times the mutations occur for no apparent reason.

Another DNA error that can lead to leukemia is a translocation. A translocation is the transfer of DNA from one chromosome to another. This abnormality can turn on oncogenes which causes rapid cell division.

Researchers have identified a number of factors that may make a person more likely to develop leukemia. These risk factors include:

  • Exposure to high levels of radiation. Patients who have received radiation therapy as treatment for other forms of cancer have an increased risk of developing leukemia later in life. In addition, people exposed to radiation from atomic blasts (such as those in Japan during World War II) and nuclear accidents have an increased risk of developing the disease. There have been numerous studies examining the relationship of power lines to leukemia but to date, there is no definitive evidence that they cause an increased risk of cancer.
  • Exposure to certain chemicals. Exposure to high levels of certain chemicals, including benzene (a chemical in gasoline and cigarette smoke) and formaldehyde, can increase a person’s risk of developing leukemia.
  • Chemotherapy. Patients treated with certain chemotherapy drugs, including alkylating agents, are at an increased risk of developing leukemia later in life. The risk appears to increase with individuals who receive a higher-than-standard dose of chemotherapy drugs.
  • Down syndrome and other specific genetic diseases. Patients with certain diseases caused by abnormal chromosomes, including Down syndrome, may have an increased risk of developing leukemia.
  • Smoking. Cigarette smoking increases a person’s risk of developing leukemia.
  • Human T-cell leukemia virus-I (HTLV-I). This virus is responsible for the development of a rare type of chronic lymphocytic leukemia.
  • Myelodysplastic syndrome. This blood disease increases a person’s risk of developing acute myeloid leukemia.
  • Li-Fraumeni syndrome. This condition, resulting from the inheritance of a mutation in the p53 tumor suppressor gene, may increase the risk of developing leukemia in some children.

Although leukemia is associated with these risk factors, many patients with the disease have no known risk factors.

Signs and symptoms of leukemia

Leukemia can cause a variety of signs and symptoms. Most of the general symptoms are more commonly related to less serious conditions. They include:

  • Fatigue
  • Weakness
  • Weight loss
  • Fever
  • Excessive sweating, particularly at night
  • Loss of appetite

Additional signs and symptoms vary depending on the exact type of leukemia, and the areas where the disease has spread.

In cases of chronic leukemia, symptoms may not appear for a long time because in its early stages, the cells function almost normally. In fact, the disease is often discovered during a routine physical examination, before symptoms have emerged. When symptoms do develop, they are normally mild and gradually become more severe.

In cases of acute leukemia, symptoms appear quickly and rapidly become more severe. Signs and symptoms of acute leukemias are often caused by a lack of normal red blood cells, white blood cells and platelets. These deficiencies can cause a number of signs and symptoms including:

  • Shortness of breath
  • Fatigue
  • Pale skin
  • Frequent infections
  • Bruising or bleeding easily
  • Frequent or severe nosebleed
  • Vomiting
  • Confusion
  • Loss of muscle control
  • Seizures

Spread of leukemia outside of the bone marrow to certain organs, the central nervous system, or other parts of the body can result in a variety of signs and symptoms including:

  • Headaches
  • Weakness
  • Seizures
  • Vomiting
  • Difficulty keeping balance
  • Blurred vision
  • Swelling of the liver or spleen
  • Abdominal swelling or discomfort

Spread of leukemia to the covering of the bone or onto the joint surfaces expands the marrow inside the bones, often causing bone or joint pain. Spread of the disease to the lymph nodes can cause symptoms including enlarged lymph nodes (swollen glands), particularly in the neck or armpit.

Spread of the cancer cells to the skin can trigger symptoms including small colored spots on the skin resembling a common rash.

When the thymus is affected by leukemia a variety of symptoms may occur. An enlarged thymus may press on the neighboring windpipe and cause coughing, shortness of breath or suffocation.

Compression of the superior vena cava by leukemia cells can result in a condition known as SVC syndrome. A life-threatening condition, SVC can result in swelling of the head and arms.

Early symptoms of leukemia may be overlooked because they may resemble symptoms of more common illnesses, such as influenza. Patients are encouraged to contact their physician when they experience any symptom of leukemia. The earlier the disease is diagnosed, the earlier treatment may begin, resulting in a better prognosis.

Diagnosis methods for leukemia

A physician who suspects that a patient may have leukemia will first obtain the patient’s medical history and perform a complete physical examination. During the physical examination, the physician will inspect the lymph nodes, spleen and liver for swelling.

Next, a variety of tests may be ordered to diagnose, classify, and monitor leukemia. Common tests include:

  • Blood tests. A complete blood count (CBC) measures the number of red blood cells, white blood cells and platelets in a sample of blood, as well as the amount of hemoglobin in the red blood cells and a number of other factors.  A blood cell count and the examination of cells under a microscope may be ordered to determine if leukemia is present. Changes in the numbers of different blood cell types and the appearance of the cells can suggest leukemia.

  • Bone marrow tests. A bone marrow aspiration and biopsy may be ordered. A bone marrow aspiration involves using a thin needle to collect a small sample of liquid bone marrow under local anesthesia. A bone marrow biopsy uses a larger needle to remove a piece of bone marrow.  Usually performed at the same time, these procedures may be ordered to determine if leukemia is present or to monitor treatment.

  • Excisional lymph node biopsy. This surgical procedure involves removing one or more lymph nodes for examination and analysis of tissue by a pathologist.

  • Lumbar puncture. Also known as a spinal tap, this procedure uses a needle to remove a sample of cerebrospinal fluid (CSF) from between the bones in the lower spine. The sample is then examined for leukemia cells. The procedure may also be ordered to deliver chemotherapy drugs into the spinal fluid when leukemia cells are located.

  • Blood chemistry tests. These tests measure the level of specific chemicals in the blood. They are used to monitor changes in liver or kidney function caused by leukemia or treatment with certain chemotherapy drugs.

  • Chest x-ray. This test uses low doses of radiation to produce images of the chest and can reveal signs of leukemia in the lungs or chest.

Additional tests include laboratory tests to diagnose and classify the leukemia. All biopsy samples (bone marrow, lymph node tissue, blood and CSF) are studied under a microscope. A number of characteristics, including the size and shape of the cells are noted in order to classify the cancer cells into specific types. Additional tests may also be ordered to study the chromosomes (cytogenetics) and additional substances in the cells.

Treatment and prevention of leukemia

As with all cancers, treatment for leukemia is usually coordinated by a cancer care team, headed by a primary care physician and/or medical oncologist. For leukemia, specialists on the team may include a hematologist, surgeon and radiation oncologist. For children, the team will include pediatric cancer specialists.

There are a variety of methods used to treat leukemia. Without prompt and successful treatment, the disease is often fatal. The exact treatment method chosen for each patient depends on the type of leukemia and the extent of the disease.

Common treatment methods include:

  • Chemotherapy. This treatment method uses powerful drugs or combinations of drugs to destroy cancer cells. Chemotherapy is the most common treatment method for leukemia. The type of chemotherapy drugs used to treat the leukemia varies based on the exact form of the disease. For treatment, the patient may receive a single drug or a combination of two or more drugs.

  • Targeted therapies. These drugs target cancer cells and block specific molecules in the cells that contribute to tumor growth. Because of this ability to target cancer cells, these therapies can be less toxic to normal tissue than chemotherapy. Some of the major advances in targeted therapies have been directed to leukemia research. The drug imatinib has become a breakthrough treatment for chronic myelogenous leukemia (CML) and is also being used for certain subtypes of acute lymphocytic leukemia. Several other targeted therapies have been approved recently for CML patients who do not respond to imatinib.

  • Radiation therapy. Radiation therapy uses high-energy rays to destroy cancer cells and shrink tumors. Most patients receive radiation directed at the spleen, the brain or other areas of the body where leukemia cells have accumulated. Other patients may receive radiation that is directed at the entire body (total-body irradiation).

  • Biological therapy. Patients with some forms of leukemia receive biological therapy. Also known as immunotherapy, this method improves the body’s natural ability to defend itself against cancer. It uses substances naturally produced by the immune system to kill leukemia cells, slow the growth of cancer cells or activate the patient’s immune system to fight the disease. In some cases, biological therapy may be used to directly attack the cancer cells. Substances that may be used include monoclonal antibodies and interferon.

  • Bone marrow/stem cell transplantation. This method allows a patient to receive high levels of chemotherapy, radiation or a combination of both. Although the high-dose treatment destroys the leukemia cells, it also destroys normal blood cells in the bone marrow. After the treatment, the patient receives an infusion of healthy stem cells through a vein. As a result, new blood cells begin to develop from the transplanted cells.

In addition to these methods, some patients may have their spleen removed if it is enlarged. Patients may receive one method of treatment or a combination of treatments. Patients with an acute form of leukemia will usually be treated immediately and aggressively. Once signs and symptoms vanish, additional therapy may be given to prevent a relapse. This is known as maintenance therapy.

Patients with a form of chronic leukemia may not require immediate treatment. A method known as watchful waiting may be recommended. In this process, the patient’s healthcare team monitors the patient’s health. Once symptoms appear or worsen, treatment is initiated to control the disease and the symptoms. Maintenance therapy may also be ordered to keep the cancer in remission.  

After treatment, patients may require regular visits to their physicians. Frequent examinations enable their physicians to detect any changes in health and treat them immediately. Checkups may include a physical examination, blood tests, x-rays, bone marrow aspiration or lumbar puncture (spinal tap).

Survival rates vary by type of leukemia. According to the Leukemia & Lymphoma Society, the 5-year survival rates for leukemia include:  

Type of leukemiaFive-year survival rate
Chronic lymphocytic leukemia (CLL)74 percent
Acute lymphocytic leukemia (ALL)65 percent
90 percent for children under age 5
Chronic myelogenous leukemia (CML)42 percent
Acute myeloid leukemia (AML)20 percent
53 percent for children under age 15

Due to advances in diagnosis and treatment, survival rates for ALL have improved since the 1970s.  For adults, the rate has improved from 38 percent to 65 percent in 1995-2001. For children with ALL, the survival rate has increased from 53 percent to 86 percent.

Currently, there is no known method of preventing most cases of leukemia because most forms are not linked to preventable lifestyle risk factors. The only exception is smoking, which is related to 20 percent of all cases of adult acute myelogenous leukemia.

Ongoing research in leukemias

A considerable amount of research is being conducted in the diagnosis, treatment and possible prevention of leukemia. Some of the areas being studied include:

  • Genetic testing. Cytogenetics is being used to test chromosomes and determine how abnormalities relate to the forms of leukemia. One promising test is known as FISH (fluorescence in situ hybridization). This advanced test analyzes specific parts of the chromosome for abnormalities and may improve the detection of chronic lymphocytic leukemia (CLL).

    Genotyping also is being researched for improving the detection and treatment of leukemia. Researchers have identified genetic variations in DNA that may help predict the effectiveness of chemotherapy with certain forms of leukemia, particularly acute lymphocytic leukemia (ALL) in children.

  • Chemotherapy drugs and targeted therapies. Researchers continue to study new drugs and drug combinations to effectively treat leukemias. The U.S. Food and Drug Administration (FDA) recently granted approval for dasatinib, a new oral treatment for CML. The drug, which is manufactured under the name Sprycel, is intended for patients who no longer respond to or can tolerate imatinib. Other drugs are being studied in clinical trials, especially combinations of targeted therapies with chemotherapy drugs for patients who become resistant to treatment. Another group of targeted therapy drugs, called FLT3 inhibitors, have shown promise in clinical trials for blocing the mutation associated with AML.

  • Biological therapy. These therapies use a patient’s immune system to provoke a response to cancer cells. Several monoclonal antibodies are used to treat different types of leukemia.

  • Scientists are also investigating ways to reduce a patient’s risk of developing resistance to chemotherapy drugs in treatment. In addition, they continue to investigate the relationship of chemotherapy drugs used to fight other cancers as a risk factor for leukemia.

  • Stem cell transplantation. Scientists participate in on-going research to advance the success of bone marrow and stem cell transplantation in leukemia patients.

  • Gene therapy. Research to alter the genes that may create or encourage growth of cancer cells. Some researchers are studying oncogenes and ways to inactivate them.

  • Vaccines. Cancer vaccines can take specific cells from a patient and use them to produce a vaccine to provoke an immune response from the cells. Clinical trials are being conducted on vaccines for both chronic and acute forms of leukemia.

There are many clinical trials being conducted around the United States for leukemia treatment. Patients should discuss their options for participating in a clinical trial with their personal physician.

Questions for your doctor about leukemias

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients or parents may wish to ask their doctor the following questions about leukemias:

  1. What signs may indicate I have leukemia?

  2. What tests are used to diagnose the disease?
  3. How will the tests be performed?
  4. When and from whom will I receive the results?
  5. What are the types of leukemia and which one do I have?
  6. What are the treatment options for my leukemia?
  7. How quickly should I have the treatment?

  8. What are the risks associated with these treatments?

  9. If I need a bone marrow transplant, who can be a donor?

  10. If my child has leukemia, can I donate bone marrow?
  11. What is the prognosis for my condition?
  12. How will I know if I am in remission?
  13. How will I be monitored after treatment?
  14. What are the chances that my leukemia will return?
  15. Are my children at higher risk for leukemia if I have the disease?
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