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Chronic leukemias are types of cancer that start in the bone marrow, where blood cells are produced. The term "chronic" indicates that the disease typically progresses more slowly compared to acute leukemias. There are three main types of chronic leukemia:
Chronic Lymphocytic Leukemia (CLL):
This is a cancer of the bone marrow characterized by the uncontrolled growth of a specific type of white blood cell called lymphocytes. Lymphocytes are immune system cells that help the body fight infections. In CLL, the term "chronic" denotes that the disease generally has a slow course. It most commonly affects older adults.
Chronic Myeloid Leukemia (CML):
CML is a cancer that begins in the blood-forming cells of the bone marrow. In this disease, a genetic change occurs in the early (immature) forms of myeloid cells (cells that produce red blood cells, platelets, and most types of white blood cells except lymphocytes). This change creates an abnormal BCR-ABL gene, which transforms the cell into a CML cell. Leukemia cells accumulate in the bone marrow, spread into the blood, and can eventually settle in other organs, such as the spleen. CML generally progresses slowly, but in some cases, it can transform into a more rapidly progressing and harder-to-treat acute form. While mostly diagnosed in adults, it can very rarely occur in children.
Chronic Myelomonocytic Leukemia (CMML):
CMML is a type of blood cancer considered an intermediate form between myeloproliferative diseases (excessive cell production in the bone marrow) and myelodysplastic syndrome (the bone marrow's inability to produce enough blood cells with the potential to transform into leukemia). The World Health Organization (WHO) classifies CMML as a mixed myelodysplastic/myeloproliferative disease. In this disease, a change in stem cells disrupts the normal development of a type of white blood cell called monocytes. Monocytes and other immature myeloid cells (myeloblasts and myelocytes) accumulate in the bone marrow and other organs, hindering the production of normal blood cells. Affecting approximately three out of 100,000 people annually, CMML usually occurs in older adults and is diagnosed twice as often in men than in women. It has rarely been reported in older children and young adults.
What are chronic leukemias?
Chronic Lymphocytic Leukemia (CLL):
This is a cancer of the bone marrow characterized by the uncontrolled growth of a specific type of white blood cell called lymphocytes. Lymphocytes are immune system cells that help the body fight infections. In CLL, the term "chronic" denotes that the disease generally has a slow course. It most commonly affects older adults.
Chronic Myeloid Leukemia (CML):
CML is a cancer that begins in the blood-forming cells of the bone marrow. In this disease, a genetic change occurs in the early (immature) forms of myeloid cells (cells that produce red blood cells, platelets, and most types of white blood cells except lymphocytes). This change creates an abnormal BCR-ABL gene, which transforms the cell into a CML cell. Leukemia cells accumulate in the bone marrow, spread into the blood, and can eventually settle in other organs, such as the spleen. CML generally progresses slowly, but in some cases, it can transform into a more rapidly progressing and harder-to-treat acute form. While mostly diagnosed in adults, it can very rarely occur in children.
Chronic Myelomonocytic Leukemia (CMML):
CMML is a type of blood cancer considered an intermediate form between myeloproliferative diseases (excessive cell production in the bone marrow) and myelodysplastic syndrome (the bone marrow's inability to produce enough blood cells with the potential to transform into leukemia). The World Health Organization (WHO) classifies CMML as a mixed myelodysplastic/myeloproliferative disease. In this disease, a change in stem cells disrupts the normal development of a type of white blood cell called monocytes. Monocytes and other immature myeloid cells (myeloblasts and myelocytes) accumulate in the bone marrow and other organs, hindering the production of normal blood cells. Affecting approximately three out of 100,000 people annually, CMML usually occurs in older adults and is diagnosed twice as often in men than in women. It has rarely been reported in older children and young adults.