Hairy cell leukemia is a type of cancer in which the bone marrow makes too many lymphocytes (a type of white blood cell).
Hairy cell leukemia is a cancer of the blood and bone marrow. This rare type of leukemia gets worse slowly or does not get worse at all. The disease is called hairy cell leukemia because the leukemia cells look "hairy" when viewed under a microscope.
Normally, the bone marrow makes blood stem cells (immature cells) that develop into mature blood cells over time. A blood stem cell may become a myeloid stem cell or a lymphoid stem cell.
The myeloid stem cell develops into one of three types of mature blood cells:
The lymphoid stem cell develops into a lymphoblast cell and then into one of three types of lymphocytes (white blood cells):
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In hairy cell leukemia, too many blood stem cells develop into lymphocytes. These lymphocytes are abnormal and do not become healthy white blood cells. They may also be called leukemic cells. The leukemic cells can build up in the blood and bone marrow so there is less room for healthy white blood cells, red blood cells, and platelets. This may cause infection, anemia, and easy bleeding. Some of the leukemia cells may collect in the spleen and cause it to swell.
This summary is about hairy cell leukemia. See the following PDQ summaries for information about other types of leukemia:
Gender and age may affect the risk of developing hairy cell leukemia.
Anything that increases your chance of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. People who think they may be at risk should discuss this with their doctor. The cause of hairy cell leukemia is unknown. It occurs more often in older men.
Possible signs of hairy cell leukemia include tiredness, infections, and pain below the ribs.
These and other symptoms may be caused by hairy cell leukemia. Other conditions may cause the same symptoms. A doctor should be consulted if any of the following problems occur:
Tests that examine the blood and bone marrow are used to detect (find) and diagnose hairy cell leukemia.
The following tests and procedures may be used:
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Certain factors affect treatment options and prognosis (chance of recovery).
The treatment options may depend on the following:
The prognosis (chance of recovery) depends on the following:
Treatment often results in a long-lasting remission (a period during which some or all of the signs and symptoms of the leukemia are gone). If the leukemia returns after it has been in remission, retreatment often causes another remission.
There is no standard staging system for hairy cell leukemia.
Staging is the process used to find out how far the cancer has spread. Groups are used in place of stages for hairy cell leukemia. The disease is grouped as untreated, progressive, or refractory.
Untreated hairy cell leukemia
The hairy cell leukemia is newly diagnosed and has not been treated except to relieve symptoms such as weight loss and infections. In untreated hairy cell leukemia, some or all of the following conditions occur:
Progressive hairy cell leukemia
In progressive hairy cell leukemia, the leukemia has been treated with either chemotherapy or splenectomy (removal of the spleen) and one or both of the following conditions occur:
There are three ways that cancer spreads in the body.
When cancer cells spread outside the blood, a solid tumor may form. This process is called metastasis. The three ways that cancer cells spread in the body are:
The new (metastatic) tumor is the same type of cancer as the primary cancer. For example, if leukemia cells spread to the brain, the cancer cells in the brain are actually leukemia cells. The disease is metastatic leukemia, not brain cancer.
Relapsed hairy cell leukemia has come back after treatment. Refractory hairy cell leukemia has not responded to treatment.
There are different types of treatment for patients with hairy cell leukemia.
Different types of treatment are available for patients with hairy cell leukemia. Some treatments are standard (the currently used treatment), and some are being tested in clinical trials. A treatment clinical trial is a research study meant to help improve current treatments or obtain information on new treatments for patients with cancer. When clinical trials show that a new treatment is better than the standard treatment, the new treatment may become the standard treatment. Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.
Four types of standard treatment are used:
Watchful waiting
Watchful waiting is closely monitoring a patient's condition, without giving any treatment until symptoms appear or change.
Chemotherapy
Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy). When chemotherapy is placed directly into the spinal column, an organ, or a body cavity such as the abdomen, the drugs mainly affect cancer cells in those areas (regional chemotherapy). The way the chemotherapy is given depends on the type and stage of the cancer being treated. Cladribine and pentostatin are anticancer drugs commonly used to treat hairy cell leukemia. These drugs may increase the risk of developing other types of cancer, especially Hodgkin lymphoma and non-Hodgkin lymphoma. Long-term follow up for second cancers is very important.
Biologic therapy
Biologic therapy is a cancer treatment that uses the patient’s immune system to fight cancer. Substances made by the body or made in a laboratory are used to boost, direct, or restore the body’s natural defenses against cancer. This type of cancer treatment is also called biotherapy or immunotherapy. Interferon alfa is a biologic agent commonly used to treat hairy cell leukemia. For relapsed or refractory patients, a biologic agent called rituximab may be used.
Surgery
Splenectomy is a surgical procedure to remove the spleen.
New types of treatment are being tested in clinical trials.
This summary section describes treatments that are being studied in clinical trials. It may not mention every new treatment being studied. Information about clinical trials is available from the NCI Web site.
Stem cell transplant
Stem cell transplant is a method of giving chemotherapy and replacing blood-forming cells destroyed by the cancer or cancer treatment. Stem cells (immature blood cells) are removed from the blood or bone marrow of a brother or sister and are frozen and stored. After the chemotherapy is completed, the stored stem cells are thawed and given back to the patient through an infusion. These reinfused stem cells grow into (and restore) the body’s blood cells.
Patients may want to think about taking part in a clinical trial.
For some patients, taking part in a clinical trial may be the best treatment choice. Clinical trials are part of the cancer research process. Clinical trials are done to find out if new cancer treatments are safe and effective or better than the standard treatment.
Many of today's standard treatments for cancer are based on earlier clinical trials. Patients who take part in a clinical trial may receive the standard treatment or be among the first to receive a new treatment.
Patients who take part in clinical trials also help improve the way cancer will be treated in the future. Even when clinical trials do not lead to effective new treatments, they often answer important questions and help move research forward.
Patients can enter clinical trials before, during, or after starting their cancer treatment.
Some clinical trials only include patients who have not yet received treatment. Other trials test treatments for patients whose cancer has not gotten better. There are also clinical trials that test new ways to stop cancer from recurring (coming back) or reduce the side effects of cancer treatment.
Clinical trials are taking place in many parts of the country. See the Treatment Options section that follows for links to current treatment clinical trials. These have been retrieved from NCI's clinical trials database.
Follow-up tests may be needed.
Some of the tests that were done to diagnose the cancer or to find out the stage of the cancer may be repeated. Some tests will be repeated in order to see how well the treatment is working. Decisions about whether to continue, change, or stop treatment may be based on the results of these tests. This is sometimes called re-staging.
Some of the tests will continue to be done from time to time after treatment has ended. The results of these tests can show if your condition has changed or if the cancer has recurred (come back). These tests are sometimes called follow-up tests or check-ups.
A link to a list of current clinical trials is included for each treatment section. For some types or stages of cancer, there may not be any trials listed. Check with your doctor for clinical trials that are not listed here but may be right for you.
If the patient's blood cell counts are not too low and there are no symptoms, treatment may not be needed and the patient is carefully watched for changes in his or her condition. If blood cell counts become too low or symptoms appear, initial treatment may include the following:
Check for U.S. clinical trials from NCI's PDQ Cancer Clinical Trials Registry that are now accepting patients with untreated hairy cell leukemia.
Treatment for progressive hairy cell leukemia may include the following:
Check for U.S. clinical trials from NCI's PDQ Cancer Clinical Trials Registry that are now accepting patients with progressive hairy cell leukemia, initial treatment.
Treatment of relapsed or refractory hairy cell leukemia may include the following:
Check for U.S. clinical trials from NCI's PDQ Cancer Clinical Trials Registry that are now accepting patients with refractory hairy cell leukemia.
For more information from the National Cancer Institute about hairy cell leukemia, see the following:
For general cancer information and other resources from the National Cancer Institute, see the following:
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The PDQ cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.
Text describing the way cancer spreads in the body was added to the Stages section.
Last Modified: 2008-08-01