Chronic lymphocytic leukemia (CLL) is a type of cancer that affects the lymphocytes, a type of white blood cell. CLL cancer cells are found mostly in the blood and bone marrow, and it doesn’t form tumors.

A similar form of cancer, small lymphocytic lymphoma (SLL) — which also affects the lymphocytes but originates in the lymph nodes — can form tumors, however.

Doctors stage the condition by looking at factors in your blood and changes in the size of some organs, such as lymph nodes and spleen.

Most people with a diagnosis of CLL are older adults. Stage 0 often requires no treatment. If you do have treatment for stage 0 CLL, you may want to take steps to manage your overall health and energy levels while protecting yourself against infection.

There are two systems to stage CLL: the Rai system and the Binet system.

The Rai system is used to measure lymphocytes in the blood and bone marrow. For a diagnosis of CLL, you must have a high concentration of monoclonal lymphocytes in the blood. “Monoclonal” means that the lymphocytes had the same original white blood cell. This condition is known as lymphocytosis.

At Rai stage 0 CLL, you’ll have lymphocytosis. However, there’s no enlargement of your lymph nodes or organs. You have near-normal red blood cell and platelet counts. In later stages of CLL, your tests will show low blood counts or lymph node or organ enlargement in addition to lymphocytosis.

If your CLL ever progresses to the later stages, your tests will show low blood counts or lymph node or organ enlargement in addition to lymphocytosis.

The other CLL staging system, the Binet system, takes into account your organs, lymph nodes, and blood counts. It doesn’t take into account lymphocytosis.

Many people with stage 0 CLL don’t have any symptoms. They continue with their regular routine and make no changes to their lifestyle.

On the other hand, if you have symptoms, have low blood counts, or have large lymph node growth, your doctor will typically recommend treatment.

In such a case, you may have to make some changes to your schedule to accommodate regular doctor’s appointments. If you’re receiving active treatment, you may experience side effects, such as fatigue, which affect your energy levels.

You may also wish to take more precautions while on immunosuppressant medications to avoid getting sick.

Stage 0 CLL is considered a “low risk” stage. The standard of care calls for a watch-and-wait approach in which you’re closely monitored by your doctor but don’t receive active treatment.

The watch-and-wait approach typically includes a doctor’s visit and blood tests every 3 months. At the end of 12 months, you and your doctor can decide whether to continue monitoring or to begin active treatment.

Many people with stage 0 CLL will stay with this approach for many years. Starting treatment earlier than necessary doesn’t improve outcomes. There are also side effects and risks of CLL treatments. And over time, your body may become resistant to some medications that you may need in later stage CLL treatment.

Your doctor may recommend treatment for stage 0 CLL if you have what the guidelines of the International Workshop on Chronic Lymphocytic Leukemia (iwCLL) call “active disease.” Some signs of active disease include:

  • prolonged fever
  • ongoing night sweats
  • extreme fatigue
  • significant weight loss

Treatment for stage 0 CLL may include:

  • Targeted therapy: This therapy works on cells at the molecular level. This is the most common treatment used in CLL. Examples of targeted therapy drugs for CLL are ibrutinib, venetoclax, acalabrutinib, rituximab, and obinutuzumab.
  • Immunotherapy: This therapy works on the immune system to help fight the cancer. An example of immunotherapy for CLL is lenalidomide.
  • Chemotherapy: Also a form of targeted therapy, chemotherapy kills the cancerous cells directly. It’s not as heavily used as it once was. Examples of chemotherapy drugs include bendamustine, chlorambucil, fludarabine, and cyclophosphamide.

During the watch-and-wait period, you may want to prioritize attending doctor’s appointments and getting blood tests. It may help to keep a log of symptoms, such as changes in weight and energy levels.

If you receive treatment for stage 0 CLL, the side effects you experience may vary depending on the type of medication and your personal health. The Leukemia and Lymphoma Society has an online resource for specific side effects and how to manage each one.

While on immunotherapy, you may want to follow nutrition guidelines for immunosuppressed people. This can help protect you from sickness your immune system would otherwise prevent. Some general tips include:

  • Avoid raw or undercooked meat or eggs.
  • Avoid soft or unpasteurized cheese or dairy products.
  • Wash fruits and vegetables before eating or handling.

Whether you’re in active treatment or watchful waiting, you may want to take steps toward a healthy lifestyle, including:

  • stress management
  • exercise
  • healthy eating
  • quality sleep
  • avoiding tobacco, drugs, and alcohol
  • staying hydrated

The average age of CLL diagnosis is 70 years. The condition rarely affects those under the age of 40.

People with a diagnosis of stage 0, 1, or 2 CLL can live for 5 to 20 years without treatment. More than half of those with stage 0 CLL live 12.5 years or more.

Chronic lymphocytic leukemia is a cancer of the blood. Doctors usually monitor the blood counts and symptoms of those with stage 0 CLL. Treatment is only necessary if you have symptoms of active disease.

You can manage side effects of CLL treatment through healthy living and avoiding risks of infection.