Chronic lymphocytic leukemia (CLL) is one of the chronic lymphoproliferative disorders (lymphoid neoplasms). According to the WHO classification, B cell chronic lymphocytic leukemia is considered to be identical (ie, one disease at different stages) to the mature (peripheral) B cell neoplasm small lymphocytic lymphoma [1-3]. It is characterized by a progressive accumulation of functionally incompetent lymphocytes, which are monoclonal in origin.
The staging and prognosis of CLL will be reviewed here. The pathophysiology, clinical manifestations, diagnosis, and treatment of B cell CLL, including hematopoietic cell transplantation, are discussed separately on the appropriate topic reviews. (See "Pathologic features, diagnosis, and differential diagnosis of chronic lymphocytic leukemia" and "Clinical manifestations, pathologic features, and diagnosis of small lymphocytic lymphoma" and "Overview of the treatment of chronic lymphocytic leukemia" and "Overview of the complications of chronic lymphocytic leukemia".)
There had been a general belief that chronic lymphocytic leukemia (CLL) is an indolent disease associated with a prolonged (ie, 10 to 20 years) clinical course, and that the eventual cause of death may be unrelated to CLL. However, this observation is true for less than 30 percent of all CLL cases. Some patients die rapidly, within two to three years from diagnosis, from complications or causes directly related to CLL. Other patients live for 5 to 10 years with an initial course that is relatively benign followed by a terminal phase lasting one to two years. During this terminal phase there is considerable morbidity, both from the disease itself and from complications of therapy. The biologic reasons behind this clinical variability are under intense study, and are discussed below. (See 'Clinical staging and prognosis' below.)
During the initial asymptomatic phase, patients are able to maintain their usual lifestyles, but during the terminal phase the performance status is poor, with recurring need for hospitalization. The most frequent causes of death are severe systemic infection (especially pneumonia and septicemia), bleeding, and inanition with cachexia. Spontaneous clinical regression has been reported, but is rare .
CLINICAL STAGING AND PROGNOSIS
As noted above, the natural history of chronic lymphocytic leukemia (CLL) is extremely variable, with survival times from initial diagnosis that range from 2 to 20 years, and a median survival of approximately 10 years. Until the mid 1970s, there were no reliable clinically applicable criteria that would allow the prospective separation of patients with a poor outlook for survival from those with an excellent prognosis. This difficulty forced physicians to make decisions concerning the need for, and timing of, therapeutic intervention in their patients with CLL, almost exclusively on an empiric basis.