A cancer that involves proliferation of the white blood cells known as lymphocytes. Unlike normal lymphocytes, which are involved in maintaining the body’s immunity against invading microorganisms and other foreign invaders, the cancerous cells have little immune function and tend to accumulate in the bone marrow, bloodstream, spleen, and lymph nodes.
A malignancy in which abnormal lymphocytes (usually B cells) proliferate and infiltrate body tissues, often causing lymph node enlargement and immune dysfunction. Infectious complications are common. Median life expectancy is about 4 years. Chronic lymphocytic leukemia is the most common leukemia in industrialized nations. It usually occurs in people (older men) above age 60. Its incidence rises to 20 cases per 100,000 in people over 80. In 2008 the American Cancer Society estimated that 15,100 people would be diagnosed with CLL and that 4,400 would die of the disease. The timing of treatment and the prognosis in CLL depend on the stage of the disease. Staging includes such factors as the number of abnormal lymphocytes in the bloodstream, how quickly they double, and the presence of lymphadenopathy, organomegaly, or cytopenias.
A hematological malignancy marked by an abundance of malignant, fully developed white blood cells and swollen lymph nodes.