# Chronic lymphocytic leukemia
What is it
Chronic lymphocytic leukemia (CLL) is a cancer in which the body produces too many immature lymphocytes (a type of white blood cell). These cells originate in the bone marrow and accumulate in the blood, lymph nodes, and spleen. The word "chronic" means that the disease usually progresses slowly, in contrast to acute forms that worsen rapidly.
CLL occurs mainly in adults aged 70 years or older, although it can also occur in younger people. It is one of the most common blood cancers in the Western world. The disease does not develop because of anything you did or did not do — it is the result of random genetic changes in lymphocytes.
Causes
The exact cause of CLL is unknown. It develops when certain lymphocytes acquire mutations (changes in their DNA), which means they can no longer die properly and multiply without limit. This usually happens randomly and is not hereditary, although relatives of CLL patients have a slightly higher risk.
Some factors that may increase the risk are age (usually after 60 years), male sex, and certain genetic disorders, but these do not explain why someone develops CLL. Exposure to certain substances or chemicals is not a proven cause.
How the disease progresses
CLL progresses very slowly in many people. Some patients have no symptoms for years and do not need treatment. The disease is often discovered by chance during a routine blood test for another reason.
In others, the condition gradually worsens. The number of abnormal lymphocytes increases, lymph nodes may grow, and the spleen or liver may swell. Sometimes CLL remains stable for decades; in other cases, growth accelerates.
A small percentage of patients (5–10%) experience a more aggressive transformation, in which CLL progresses to a more advanced form. This is called Richter transformation. This usually happens after several years.
Symptoms by phase
**Early stages (often without symptoms)**
Many people notice nothing from CLL. The disease is discovered when the number of white blood cells happens to be elevated during a blood test.
**With growth of lymph nodes and organs**
- Swollen lymph nodes in the neck, armpits, or groin (usually not painful)
- Feeling of fullness in the abdomen (due to enlargement of the spleen or liver)
- Unintended weight loss
- Fatigue and weakness
- Night sweats (sometimes so severe that clothes become soaked)
- Increased susceptibility to infections (due to decrease in healthy white blood cells)
**With progression**
- Anemia symptoms: pallor, shortness of breath, dizziness
- Bleeding tendency: bruising, nosebleeds, or slowly healing wounds
- Fever without a clear cause
- With Richter transformation: suddenly much worse symptoms, rapidly declining health
What it means for daily life
For many CLL patients in the early stage, little changes in daily life. The disease does not need to be a direct limitation as long as treatment is not necessary.
Once lymph nodes grow or the disease progresses, fatigue and malaise can limit activities. Infections are a risk because the immune system becomes weakened. This may mean that caution is warranted with crowds, hygiene becomes extra important, and certain vaccinations may not be as effective.
During treatment, side effects can occur that affect daily functioning. This varies greatly and depends on the chosen regimen. Some patients feel well and continue working; others experience more fatigue or other effects.
The psychological aspect should not be forgotten: a cancer diagnosis brings emotional burden, even if physical symptoms are initially limited.
Outlook
The outcome of CLL is very individual and depends on many factors: age, biological characteristics of the cancer cell, stage at discovery, and how well the body responds to treatment.
For population-level information: in the period 2010–2015, the five-year survival rate for CLL in many Western countries was approximately 80–85%, but this figure says nothing about any specific individual. More recent treatments have improved outcomes for many, especially for patients who respond well to targeted therapies.
Many patients with CLL live for years with the disease without serious consequences. Some achieve long-term remission (no detectable disease). Others experience cyclical periods of growth and stabilization. Progression and response to treatment are unpredictable for each individual.
Medical progress—particularly better targeted therapies and improved understanding of the disease—is ongoing. Research is looking at how treatment can be tailored to an individual's specific tumor profile and how sustained control without continuous treatment may become more feasible.
Frequently asked questions
**Is CLL hereditary?**
CLL itself is not hereditary, but those with a family member who has CLL carry a slightly elevated risk. This does not mean you will definitely develop it—many people with that risk never get CLL. Genetic counseling can be worthwhile if multiple family members are affected.
**Do you need treatment immediately once CLL is diagnosed?**
No. In many patients with early-stage, stable CLL, doctors recommend watchful waiting ("watch and wait") without immediate treatment. This prevents unnecessary side effects while still maintaining oversight. Once the disease actively progresses or causes symptoms, treatment is usually started.
**Can you go into remission with CLL?**
Yes. Many patients achieve remission with modern treatments, meaning the disease is no longer detectable on tests. How long this lasts varies. Some remain stable for years; others see the disease return. Monitoring therefore remains important.
**How often do you need to go to the hospital for check-ups?**
This depends on your phase and treatment. During watchful waiting periods, this is usually several times a year. During active treatment, it may be weekly to monthly. After completing treatment, regular follow-up appointments follow. Discuss this with your own medical team.
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_This information never replaces a doctor's judgment. Always discuss your situation with your own healthcare provider._