Leukemia is a term for cancers of the blood cells. Leukemia starts in blood-forming tissues such as the bone marrow. Your bone marrow makes the cells which will develop into white blood cells, red blood cells, and platelets. Each type of cell has a different job:

• White blood cells help your body fight infection
• Red blood cells deliver oxygen from your lungs to your tissues and organs
• Platelets help form clots to stop bleeding

When you have leukemia, your bone marrow makes large numbers of abnormal cells. This problem most often happens with white blood cells. These abnormal cells build up in your bone marrow and blood. They crowd out the healthy blood cells and make it hard for your cells and blood to do their work.

Chronic lymphocytic leukemia (CLL) is a type of chronic leukemia. "Chronic" means that the leukemia usually gets worse slowly. In CLL, the bone marrow makes abnormal lymphocytes (a type of white blood cell). When the abnormal cells crowd out the healthy cells, it can lead to infection, anemia, and easy bleeding. The abnormal cells can also spread outside the blood to other parts of the body. CLL is one of the most common types of leukemia in adults. It often occurs during or after middle age. It is rare in children.

CLL happens when there are changes in the genetic material (DNA) in bone marrow cells. The cause of these genetic changes is unknown, so it's hard to predict who might get CLL. There are a few factors that might raise your risk.

It is hard to predict who will get CLL. There are a few factors that could raise your risk:

• Age - your risk goes up as you get older. Most people who are diagnosed with CLL are over 50.
• Family history of CLL and other blood and bone marrow diseases
• Racial/ethnic group - CLL is more common in whites than in people from other racial or ethnic groups
• Exposure to certain chemicals, including Agent Orange, a chemical that was used in the Vietnam War

In the beginning, CLL does not cause any symptoms. Later, you can have symptoms such as:

• Swollen lymph nodes - you may notice them as painless lumps in the neck, underarm, stomach, or groin
• Weakness or feeling tired
• Pain or a feeling of fullness below the ribs
• Fever and infection
• Easy bruising or bleeding
• Petechiae, which are tiny red dots under the skin. They are caused by bleeding.
• Weight loss for no known reason
• Drenching night sweats

Your health care provider may use many tools to diagnose CLL:

• A physical exam
• A medical history
• Blood tests, such as a complete blood count (CBC) with differential and blood chemistry tests. Blood chemistry tests measure different substances in the blood, including electrolytes, fats, proteins, glucose (sugar), and enzymes. Specific blood chemistry tests include a basic metabolic panel (BMP), a comprehensive metabolic panel (CMP), kidney function tests, liver function tests, and an electrolyte panel.
• Flow cytometry tests, which check for leukemia cells and identify which type of leukemia it is. The tests can be done on blood, bone marrow, or other tissue.
• Genetic tests to look for gene and chromosome changes

If you are diagnosed with CLL, you may have additional tests to see whether the cancer has spread. These include imaging tests and bone marrow tests.

Treatments for CLL include:

• Watchful waiting, which means that you don't get treatment right away. Your health care provider regularly checks to see if your signs or symptoms appear or change.
• Targeted therapy, which uses drugs or other substances that attack specific cancer cells with less harm to normal cells.
• Chemotherapy
• Radiation therapy
• Immunotherapy
• Chemotherapy with bone marrow or stem cell transplant

The goals of treatment are to slow the growth of the leukemia cells and to give you long periods of remission. Remission means that the signs and symptoms of cancer are reduced or have disappeared. The CLL may come back after remission, and you may need more treatment.

NIH: National Cancer Institute