Alternative names: Chronic lymphoid leukemia.
Chronic Lymphocytic Leukemia (CLL) is a type of cancer that starts from white blood cells (lymphocytes) in the bone marrow, from where it invades the blood. Leukemia cells tend to build up in the body over time, but in many cases people don't have any symptoms for at least a few years. In time, it can also invade other parts of the body, including the lymph nodes, liver, and spleen. Compared to other types of leukemia, CLL usually grows slowly.
Leukemia is different from other types of cancer that start in organs such as the lungs, colon, or breast and then spread to the bone marrow. Cancers that start elsewhere and then spread to the bone marrow are not leukemia.
Doctors have found that there seem to be 2 different kinds of CLL:
The leukemia cells from these 2 types look alike, but new lab tests can tell the difference between them.
Each year, nearly 7,000 people in the United States learn that they have Chronic Lymphocytic Leukemia (CLL). The disease is very uncommon in individuals under 45 years of age. At the time of diagnosis, 95% of patients are over age 50 and the incidence of the disease increases dramatically thereafter.
CLL results from an acquired (not inherited) injury to the DNA of a single cell in the bone marrow. This injury is not present at birth. Scientists do not yet understand what produces this change in the DNA of CLL patients.
This change in the cell's DNA confers a growth and survival advantage on the cell, which becomes abnormal and malignant (leukemic). The result of this injury is the uncontrolled growth of lymphocytic cells in the marrow leading invariably to an increase in the concentration of lymphocytes in the blood. The leukemic cells that accumulate in the marrow in CLL do not impede normal blood cell production as profoundly as in the case of acute lymphocytic leukemia. This important distinction from acute leukemia accounts for the less severe early course of the disease.
Unlike the other three major types of leukemia, Chronic Lymphocytic Leukemia is not associated with high-dose radiation or benzene exposures. First-degree relatives of patients with the disease have about a threefold greater likelihood of getting the disease than other people. This should be put into perspective, however. For example, the 60-year-old sibling or offspring of a patient with chronic lymphocytic leukemia would have three chances in 10,000 of developing the disease compared to the one chance in 10,000 for a 60-year-old person without a family history of the disease.
The symptoms of chronic lymphocytic leukemia usually develop gradually. Patients tire more easily and may feel short of breath when physically active. They may lose weight. They may experience frequent infections of the skin, lungs, kidneys or other sites.
Early in the disease, chronic lymphocytic leukemia may have little effect on a person's well-being. The disease may be discovered after finding an abnormal blood count during the course of a routine medical examination or while the patient is under care for an unrelated condition. The report of an elevated white blood cell count is the most common clue that leads a physician to consider the diagnosis of chronic lymphocytic leukemia. These large numbers of leukemic lymphocytes (white cells) can collect in the lymphatic system and the lymph nodes may become enlarged.
To diagnose the disease, the blood and, in most cases, the marrow cells must be examined. The white cell count invariably increases in the blood. A bone marrow examination will also show a marked increase in the proportion of lymphocytes in the marrow, often accompanied by some decrease in the normal marrow cells. Low platelet counts and low red cell counts (anemia) may be present, but are usually only slightly decreased in the early stage of the illness.
The pattern of the lymphocytes in the biopsy of the marrow can be one useful factor in determining the probable rate of progression of the disease. In addition, a sample of marrow is examined to determine if there is an abnormality of chromosomes. The examination of marrow cells to determine if an abnormality of chromosomes is present is referred to as a cytogenetics analysis.
Depending on the place in lymphocytic cell development in which the malignant transformation occurs, the leukemic cells may be principally B cells, T cells, or NK cells. Most patients have a B cell type of leukemia. A minority have T or NK cell types. These distinctions may be accounted for by the malignant transformation occurring after the common lymphocyte has differentiated into one of the three types of lymphocytes. The malignant event (mutation of DNA) would, therefore, occur at the point, or after, the early specialized lymphocytes were formed.
Determining the immunophenotype of the lymphocytes in the blood or marrow is important. This distinguishes whether the lymphocytes that accumulate are derived from a malignant transformation of a lymphocyte in the B cell developmental pathway or the T cell developmental pathway. The T cell type of disease, called T cell chronic lymphocytic leukemia, is very infrequent. When it occurs, it may affect the skin, nervous system and lymph nodes more often and is more rapidly progressive than is the B cell type. Immunophenotyping also permits an assessment of whether the lymphocytes in the blood are derived from a single malignant cell (whether they are monoclonal or not). The test for clonality is important because it distinguishes leukemia from the very infrequent increase in the blood lymphocytes in adults that is not the result of a malignant transformation characteristic of cancer.
Another very important test that is performed is the measurement of the concentration of gamma globulins (immunoglobulins) in the blood. Immunoglobulins are proteins called antibodies that the B cells of healthy individuals make to protect themselves from infection. They are often deficient in persons with chronic lymphocytic leukemia. The leukemic B lymphocytes do not make protective antibodies effectively. At the same time, the leukemia also acts to prevent residual normal lymphocytes from doing so. This inability to make antibodies efficiently makes CLL patients susceptible to infections.
CLL is one of the cancers that may respond to LDN.
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