Chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is a type of cancer that affects the blood and bone marrow. In CLL, the bone marrow produces too many lymphocytes, which are a type of white blood cell. B cell lymphocytes can begin to collect in the blood, spleen, lymph nodes, and bone marrow; these cells malfunction and crowd out healthy blood cells. CLL is divided into slow-growing (indolent) and fast-growing variants.

Most individuals have no symptoms when they are first diagnosed with CLL. Around five to 10% of patients may experience fever, fatigue, unexplained weight loss, loss of appetite, painless swelling of the lymph nodes, enlargement of the spleen, and/or anemia. These symptoms often worsen over time. Patients with CLL also have an increased risk of developing serious infections. The exact cause of CLL is unknown, but risk factors include a family history of CLL, tobacco use, or environmental exposure to Agent Orange, ionizing radiation, certain insecticides. Diagnosis is typically by testing the blood for high numbers of mature lymphocytes and smudge cells.

Asymptomatic patients of CLL are often managed by watchful waiting and monitoring for other infections, and there is currently no evidence that early intervention can alter the course of the disease. Those with significant symptoms are treated with chemotherapy, immunotherapy, or a combination of both, depending on the individual's age, physical condition, and whether they have the del(17p) or TP53 mutations.

CLL is the most common type of leukemia in the Western world. It most commonly affects individuals over the age of 65, due to the accumulation of genetic mutations that occur over time. CLL is rarely seen in individuals less than 40 years old. Men are more commonly affected than women, although the average lifetime risk for both genders are similar (around 0.5-1%). It represented less than 1% of deaths from cancer between 1980 and 2015.