Chronic lymphocytic leukaemia (CLL) is a serious condition, but it develops slowly. If you're diagnosed with CLL, you might not need treatment right away. CLL can't usually be permanently cured, but treatment can often keep the cancer cells under control for a while, often for years.

The name explains a couple of things about this condition. 'Chronic' means CLL can take a long time to progress, and 'lymphoid' tells you that it affects a particular group of white blood cells.

CLL happens because your body's process for making white blood cells, called haematopoiesis, isn't working correctly. There are too many lymphocytes (a type of white blood cell) and many of them are not fully mature. Over time, the lymphocytes can start crowding out your red blood cells and platelets.

You can learn more about blood cells and haematopoiesis, in our general information about leukaemia.

What are the symptoms of CLL?

Many people with CLL don't feel unwell at first. It's often picked up by chance, when you have a blood test for another reason.

The main symptom is usually swollen glands in your armpits, neck or groin. Other symptoms of CLL can include:

  • Swelling in your abdomen
  • Feeling very tired
  • Pale skin
  • Feeling breathless
  • Unusual bleeding
  • Bruises
  • Getting lots of infections
  • Fever
  • Losing weight
  • Night sweats
What causes CLL?

We don't know what causes CLL. Most commonly, it appears between the ages of 60 and 80. It occurs more often in men than in women.

CLL is more likely to happen when you have a close relative with the condition, but we can't identify a specific gene that explains it. If someone in your family has CLL, the risk that you will also have it is still small.

How is CLL diagnosed?

A blood test that shows high levels of lymphocytes is often the first sign of CLL. If CLL is suspected, you'll be offered further blood tests to confirm the diagnosis. You may also be offered a bone marrow biopsy.

The cancer cells in your blood and bone marrow can be tested for abnormal genes, to find out what type of CLL you have. This information is important because it gives an idea of the outlook, and which treatment might work best for you.

You may also be offered a chest X-ray, ultrasound scan or CT scan.

You'll have regular check-ups and blood tests to monitor your condition if you don't need treatment right away, or to check how well it is working if you do start treatment.

You can read more in our information about tests for leukaemia.

What are the stages of CLL?

Your test results will show how far the CLL has advanced. This information, called staging, gives an idea of the outlook and helps in choosing the best treatment.

The Binet staging system is the one that is used most in the UK. It has two parts, based on:

  • How many lymph glands are enlarged, and whether your spleen or liver is enlarged
  • How many white blood cells there are, and how much they have crowded out your other blood cells

The stages are ranked by the letter A (least advanced cancer), B or C (most advanced).