Hairy cell leukemia is a rare type of blood cancer that can affect adults. In people who receive treatment, the long-term outlook for hairy cell leukemia is good.

Hairy cell leukemia (HCL) occurs when bone marrow produces too many white blood cells called lymphocytes.

The disease gets its name from the hairlike projections on its cells. HCL cells can affect the bone marrow, spleen, liver, and lymph nodes.

According to the National Organization for Rare Disorders, HCL is more common in males over the age of 50 years.

HCL affects roughly 6,000 people in the United States, with around 600–800 new diagnoses each year. Around 1–2% of all adult leukemias are HCL.

In many cases, the long-term outlook for HCL is good, with people often continuing to live good-quality lives for years with medical care.

In this article, we look at the outlook and survival rates for HCL, the risk of secondary cancers, and treatment options.

Learn about the symptoms of HCL here.

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HCL is a chronic disease, and although there is no cure for it, the condition is treatable. Treatment is usually highly effective and can help people continue to live normal lives.

According to the National Cancer Institute, HCL progresses slowly or does not worsen at all.

The Leukemia and Lymphoma Society reports that the 5-year event-free survival rate for HCL is 90% in people who received initial treatment with the chemotherapy drug cladribine. This means 90% of people will still be alive 5 years after diagnosis.

Treatment with cladribine has led to roughly 85% complete remission and around 10% partial response in people with HCL.

A 2020 study looked at survival rates in 279 people diagnosed with HCL between 1980 and 2011. The median age of the participants was 59 years old. In 208 of the participants, the first-line treatments were the drugs cladribine or pentostatin.

A 10-year follow-up found that the median survival rate was 27 years overall, with 11 years of relapse-free survival. There was a relapse rate of 39%. The study concluded that people with HCL have a good long-term outlook.

Research suggests that there may be racial disparities in HCL outcomes. A 2015 study included participants of the following racial groups:

  • 93% white
  • 3.5% Asian or Pacific Islander
  • 3.5% African American

The study found that the 10-year survival rate was worse in African American participants than in those of other racial groups.

Half of African American participants were alive at the 10-year follow-up, whereas more than two-thirds of those in other racial groups were alive at the follow-up.

The researchers concluded that the biological, socioeconomic, and health system factors contributing to this disparity need further investigation.

Health equity resources

Visit our dedicated hub for an in-depth look at social disparities in health and what we can do to correct them.

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According to a 2020 study, people with HCL have an increased risk of secondary cancer.

Among 279 participants, 59 people developed at least one secondary cancer. The most common secondary cancers were prostate cancer, nonmelanoma skin cancer, and blood cancers.

The study did not find that treatment with purine analogs, such as cladribine or pentostatin, was a risk factor for secondary cancers.

However, according to the National Cancer Institute, cladribine and pentostatin may increase the risk of Hodgkin lymphoma and non-Hodgkin lymphoma.

Some research suggests that HCL and its effects on the body may increase the risk of secondary cancer.

People with HCL must attend regular cancer screenings to detect any early signs of secondary cancer.

Blood cell changes in those with HCL may result in compromised immune systems, making people more susceptible to infection or autoimmune disease.

HCL responds very well to treatment, which aims to manage the cancer rather than cure it.

Unlike with many other types of cancer, doctors may choose to wait before starting treatment.

Doctors will monitor the condition and may only begin treatment if they believe it is necessary to control it. This can help avoid any unnecessary side effects of treatment.

The type of treatment will depend on each condition but may include the following:


Cladribine and pentostatin are purine analogs, which are the first-line treatment for HCL.

According to the Hairy Cell Leukemia Foundation, both medications are highly effective treatments and can result in long-term remission.

In 2018, the Food and Drug Administration (FDA) approved another drug, moxetumomab pasudotox, to treat HCL. Doctors may use this drug in people who have not responded to standard therapies.

Immunotherapy or biologic therapy

Interferon is a drug that doctors may use to treat HCL. Interferon uses the body’s immune system to help fight off cancer. Interferon affects how cancer cells divide and helps slow tumor growth.

Doctors may also use a biologic drug called rituximab, known by the brand name Rituxan, if people with HCL have not responded to other treatments. Rituximab is an antibody that attaches to HCL cells. Doctors may also use rituximab in combination with chemotherapy as a first-line treatment.

Targeted therapies

Targeted therapies use medications or other substances to find and destroy cancer cells. Targeted therapies may cause less harm to healthy cells than other treatments, such as radiation therapy or chemotherapy.

One type of targeted therapy to treat HCL is monoclonal antibody therapy. A laboratory creates antibodies that attach to cancer cells and destroy them or prevent them from growing and spreading. The biologic drug rituximab is an example of a monoclonal antibody.


Splenectomy is a surgical procedure to remove the spleen. This may be necessary if HCL causes an enlarged spleen.

However, doctors rarely perform splenectomy for HCL because there are medications that can effectively reduce the size of the spleen.

Learn more about immunotherapy for leukemia here.

Treatments for HCL can have the following side effects:

  • Cladribine and pentostatin are usually well tolerated but can suppress the immune system, increasing the risk of infection. Both can temporarily reduce blood counts. Pentostatin may also cause nausea.
  • Moxetumomab pasudotox may cause capillary leak syndrome and hemolytic uremic syndrome, which can be serious without treatment.
  • Interferon may cause flu-like symptoms, but these will decrease over time.

Cancer treatments may also cause other side effects, such as fatigue, appetite loss, or nausea.

Before starting treatment, people can discuss any potential side effects and the risks and benefits of each treatment option with their healthcare team.

Learn more about side effects here.

HCL is a rare type of leukemia. Other types of leukemia include:

  • Acute lymphoblastic leukemia (ALL): ALL affects blood cells and the immune system and has many subtypes. ALL progresses rapidly, but treatment effectively cures the condition in many children with ALL, and adult remission is improving.
  • Acute myeloid leukemia (AML): AML progresses quickly without treatment and affects underdeveloped cells. AML can be difficult to treat, but certain treatments effectively cure AML in some people.
  • Chronic lymphocytic leukemia (CLL): CLL is the most common type of adult leukemia in Western countries. CLL can progress slowly or quickly, depending on the type. Many people with CLL have a good long-term outcome.
  • Chronic myeloid leukemia (CML): Treatment for CML is usually very effective, and it can be a manageable condition for many people.
  • Chronic myelomonocytic leukemia (CMML): CMML is a rare form of leukemia that more commonly affects older males.
  • Juvenile myelomonocytic leukemia (JMML): JMML is not very common and usually affects children under 4 years old.
  • Large granular lymphocytic leukemia (LGL): LGL also affects lymphocytes. LGL can affect both males and females and usually affects people over the age of 50 years.
  • Blastic plasmacytoid dendritic cell neoplasm (BPDCN): BPDCN is more common in males and those between 60 and 70 years of age.
  • B-cell prolymphocytic leukemia (B-PLL): B-PLL is very rare and affects white blood cells called B-lymphocytes. It usually affects older adults.
  • T-cell prolymphocytic leukemia (T-PLL): T-PLL is a rare type of leukemia and is more common in older males.

HCL is a rare type of adult leukemia. It is more common in males over the age of 50 years.

The overall outlook for people with HCL is good. Treatment with chemotherapy drugs, such as cladribine and pentostatin, is highly effective and may result in long-term remission.

Treatments for HCL may have side effects. People can discuss any treatment’s potential risks and benefits with their healthcare team.