Small lymphocytic lymphoma

Small lymphocytic lymphoma (SLL) is a type of non-Hodgkin lymphoma. It is similar to and treated in the same way as chronic lymphocytic leukaemia (CLL).

SLL develops when the body makes abnormal B-cells – the lymphoma cells. B-cells are white blood cells that fight infection. The lymphoma cells build up in lymph nodes.

The most common symptom is a painless swelling in the neck, armpit or groin. Other symptoms may include:

  • tiredness
  • weight loss
  • night sweats
  • high temperatures (fevers).

To diagnose SLL, a doctor removes an enlarged lymph node and checks it for lymphoma cells. You will also have tests and scans to find out how many groups of lymph nodes are affected. This is called staging.

SLL is slow-growing and does not always need to be treated straight away. When treatment is needed, this is usually with chemotherapy. This is often combined with targeted therapy drugs, which target the B-cells. Some people have radiotherapy.

You may be invited to join a clinical trial looking at new ways of treating SLL. You can talk about this with your lymphoma doctor.

What is small lymphocytic lymphoma (SLL)?

It is best to read this information with our general information about chronic lymphocytic leukaemia (CLL). If you have any more questions, you can ask your doctor or nurse at the hospital where you are having treatment.

Small lymphocytic lymphoma (SLL) is a slow-growing type of non-Hodgkin lymphoma (NHL). It is similar to and treated in the same way as CLL.

It develops when B-cells (also called B-lymphocytes) become abnormal. B-cells are white blood cells that fight infection.

The abnormal B-cells (lymphoma cells) build up in lymph nodes.

Causes and risk factors for SLL

The causes of SLL are not known. Like other cancers, it is not infectious and cannot be passed on to other people. It is more common as people get older. The most common age to be diagnosed with SLL is 65.

We have more information about risk factors for lymphoma.

Signs and symptoms of SLL

Often, the first sign of SLL is a painless swelling in the neck, armpit or groin. This is caused by lymphoma cells building up in the lymph nodes, which makes them bigger. Other symptoms may include loss of appetite and tiredness (fatigue).

Sometimes lymphoma cells may build up in the bone marrow, where blood cells are made. This can cause lower than normal numbers of healthy blood cells in the blood. If your body makes too few red blood cells, you may feel pale, tired, and get breathless easily. This is called anaemia. If the number of blood-clotting cells (platelets) in your blood is too low, you may bruise or bleed easily.

B symptoms

Rarely, some people also have:

  • drenching night sweats
  • high temperatures (fevers) with no obvious cause
  • unexplained weight loss.

These are called B symptoms.

Diagnosing lymphoma

The most common test for this lymphoma is to remove part or all of an enlarged lymph node (a biopsy). This may be done under local or general anaesthetic. The biopsy is then sent to a laboratory to be checked for lymphoma cells. You may also have biopsies taken from other areas of the body.

You may have some other tests, such as:

  • blood tests
  • scans such as a CT scan
  • bone marrow samples.

Doctors use these tests to find out more about the lymphoma, including which parts of the body it has spread to. This is called staging. You can read more in our information about tests for CLL.

Staging and grading SLL


The stage of the lymphoma describes which areas of the body are affected by lymphoma. This information helps doctors plan the right treatment for you.

The stage of a lymphoma is usually described using numbers from 1 to 4. Stages 1 and 2 are also called early-stage, limited or localised lymphoma. Stages 3 and 4 are also called advanced lymphoma.

As well as giving each stage a number, doctors often add the letters A or B. A means you do not have B symptoms. B means you do have B symptoms.

Sometimes the lymphoma can affect areas outside the lymph nodes. This is called extranodal lymphoma, and the stage will include the letter E (for extranodal).


Non-Hodgkin lymphomas are divided into two groups:

  • Low-grade (indolent) lymphomas, which usually grow slowly.
  • High-grade (aggressive) lymphomas, which grow more quickly.

SLL is a low-grade lymphoma and usually develops slowly. Sometimes it can change (transform) to become a high-grade lymphoma.

Treating SLL

SLL often develops slowly. Some people may not need treatment straight away, or even for months or years. This is called watch and wait

Even if you do not need treatment, you will have regular check-ups at the hospital. Your specialist will examine you and do blood tests. This is to check the levels of your red blood cells, white blood cells and platelets (a full blood count – FBC). 

Treatment depends on:

  • the stage of the lymphoma
  • whether you have symptoms that are causing problems.

The most common treatment is a combination of chemotherapy and a targeted therapy called rituximab. Most people have their treatment as an outpatient.

For most people, the aim of treatment is to get rid of as much of the lymphoma as possible. If there are no signs of lymphoma after treatment, this is called a complete remission.

After treatment, many people have a period of time with no signs of active disease. This is called remission. If the lymphoma comes back, it may be treated again and can often be controlled for many years.


Chemotherapy uses anti-cancer (cytotoxic) drugs to destroy cancer cells. It is an important treatment for SLL and can often get it into remission.

Chemotherapy can be given as tablets or into a vein (intravenously). You may be given a single drug, or 2 or more drugs together (combination chemotherapy). You can usually have chemotherapy as an outpatient.

Chemotherapy can be given on its own, but it usually given in combination with targeted therapies.

The chemotherapy treatments most often used to treat SLL are the following:

  • FCR – this is made up of the chemotherapy drugs fludarabine and cyclophosphamide, with the targeted therapy rituximab. This is given as a drip into a vein.
  • Bendamustine – this is a chemotherapy drug. It is given with rituximab, or sometimes given on its own. Bendamustine is given as a drip into a vein.
  • Chlorambucil – a this is chemotherapy drug. It is given with a targeted therapy, or sometimes given on its own. Chlorambucil comes as tablets.

Targeted therapy

Targeted therapies are sometimes known as biological therapies. They interfere with the way cancer cells grow. These drugs only ‘target’ the cancer cells, so they have less effect on healthy cells.

Monoclonal antibodies

The most commonly used type of targeted therapy is a monoclonal antibody called rituximab. Monoclonal antibody treatments used for SLL target proteins on B-cells. This makes the B-cells die.

Monoclonal antibody treatments are usually given with chemotherapy. They can be given as a drip into a vein or as an injection under the skin.

Other monoclonal antibody treatments for SLL include:

  • ofatumumab (Arzerra®), which is given with chlorambucil
  • obinutuzumab (Gazyvaro®), which is given with chlorambucil
  • alemtuzumab (Campath®), which is sometimes used to treat SLL that has come back after treatment.

B-cell receptor inhibitors

Ibrutinib (Imbruvica®) and Idelalisib (Zydelig®) are B-cell receptor inhibitors. They target the receptors (proteins) on the surface of the cells and stop the lymphoma growing and dividing.

They may be used to treat a particular type of SLL that doesn’t respond well to chemotherapy. They are also sometimes used if the lymphoma comes back after treatment. They are taken as tablets or capsules.


Steroids are drugs that are often given with chemotherapy to treat lymphomas. They help make chemotherapy more effective. They also help you feel better and can reduce feelings of sickness.

Stem cell treatment (transplants)

This treatment is sometimes used to treat lymphoma that has come back after treatment. It is an intensive treatment, so it is not suitable for everyone.

Stem cells are a type of blood cell that can make all other types of blood cells. There are two different types of stem cell treatment:

High-dose treatment with stem cell support (autologous stem cell transplant)

Some people have treatment to put the lymphoma into remission. Then some of their own stem cells are collected from their blood and stored. Then they have high doses of chemotherapy to try to destroy any remaining lymphoma cells. After this, their stem cells are returned through a drip (like a blood transfusion). The stem cells help their blood cell numbers recover from the effects of chemotherapy.

Donor transplant (allogeneic transplant)

Some people have chemotherapy to put the lymphoma into remission and are then given stem cells from another person (a donor).


Radiotherapy uses high-energy rays to destroy cancer cells, while causing as little harm as possible to healthy cells.

It may be used as a first treatment if the abnormal B-cells are contained in 1 or 2 groups of lymph nodes in the same part of the body. In some people, this may cure the SLL.

Radiotherapy can also be used to treat lymphoma that has come back in one area of lymph nodes. Your doctor may also suggest radiotherapy to treat an enlarged spleen.

Clinical trials

Your lymphoma doctor may talk to you about having treatment as part of a clinical trial. Clinical trials test new treatments or new ways of giving treatments.

Follow-up after treatment

After treatment, you will have regular check-ups. These appointments are a good opportunity for you to talk to your doctor or nurse about any concerns you have. Your doctor will want to know how you are feeling generally, and to check you are recovering from any side effects of treatment. We have more information about follow-up.

Getting support

Everyone has their own way of dealing with illness and the different emotions they experience. You may find it helpful to talk things over with family and friends or your doctor or nurse. You can also call our cancer support specialists free on 0808 808 00 00. The organisations below also offer information and support:

  • Bloodwise offers support and information to people affected by blood cancers, including lymphoma.
  • Lymphoma Action gives emotional support, advice and information on all aspects of Hodgkin lymphoma and non-Hodgkin lymphoma. It has a national network of people with lymphoma, and local groups.