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 become mature blood cells over time. A blood stem cell may become a myeloid stem cell or a lymphoid stem cell.
A myeloid stem cell becomes one of three types of mature blood cells:
A lymphoid stem cell becomes a lymphoblast cell and then one of three types of lymphocytes (white blood cells):
In hairy cell leukemia, too many blood stem cells become lymphocytes. These lymphocytes are abnormal and do not become healthy white blood cells. The abnormal lymphocytes are also called leukemia cells. The leukemia 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.
These and other signs and symptoms may be caused by hairy cell leukemia or by other conditions. Check with your doctor if you have any of the following:
In addition to asking about your personal and family health history and doing a physical exam, your doctor may perform the following tests and procedures:
The treatment options depend on the following:
The prognosis 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.
The process used to find out if cancer has spread to other parts of the body is called staging. There is no standard staging system for hairy cell leukemia.
In untreated hairy cell leukemia, some or all of the following conditions occur:
Refractory hairy cell leukemia is cancer that does not respond to treatment.
Recurrent hairy cell leukemia is cancer that has recurred (come back) after it has been treated.
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.
Watchful waiting is closely monitoring a patient's condition, without giving any treatment until signs or symptoms appear or change.
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). 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 other types of cancer, especially Hodgkin lymphoma and non-Hodgkin lymphoma. Long-term follow up for second cancers is very important. Bendamustine is another anticancer drug that is being studied to treat hairy cell leukemia.
See Drugs Approved for Hairy Cell Leukemia for more information.
Targeted therapy is a type of treatment that uses drugs or other substances to identify and attack specific cancer cells.
Rituximab is a type of monoclonal antibody that may be used to treat certain patients with hairy cell leukemia.
Other types of targeted therapies are being studied in the treatment of hairy cell leukemia, including:
See Drugs Approved for Hairy Cell Leukemia for more information.
Splenectomy is a surgical procedure to remove the spleen.
Information about clinical trials is available from the NCI website.
For information about side effects caused by treatment for cancer, visit our Side Effects page.
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.
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. Information about clinical trials supported by NCI can be found on NCI’s clinical trials search webpage. Clinical trials supported by other organizations can be found on the ClinicalTrials.gov website.
As you go through treatment, you will have follow-up tests or check-ups. Some tests that were done to diagnose or stage the cancer may be repeated 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.
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).
For information about the treatments listed below, see the Treatment Option Overview section.
Treatment of hairy cell leukemia may include the following:
You and your doctor will discuss what treatment plan is best for you.
Use our clinical trial search to find NCI-supported cancer clinical trials that are accepting patients. You can search for trials based on the type of cancer, the age of the patient, and where the trials are being done. General information about clinical trials is also available.
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, visit:
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PDQ® Adult Treatment Editorial Board. PDQ Hairy Cell Leukemia Treatment. Bethesda, MD: National Cancer Institute. Updated <MM/DD/YYYY>. Available at: https://www.cancer.gov/types/leukemia/patient/hairy-cell-treatment-pdq. Accessed <MM/DD/YYYY>. [PMID: 26389248]
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