CLL Basics
The word leukemia originates from the Greek words for "white" (leukos) and "blood" (haima).
What is CLL?
Leukemia is the most common type of blood cancer. It occurs when there is a rapid growth of abnormal blood cells in your blood marrow, which is the spongy tissue inside your bones where most of your blood is made. Leukemia begins when healthy blood cells begin to grow out of control and build up in the bone marrow, crowding out normal cells. Leukemia cells are usually immature (still developing) white blood cells, which are the cells that fight infection. Leukemia cells (the abnormal cells) may also leave the bone marrow and spill into your bloodstream, where it can spread to other organs and cause the number of white blood cells to increase.
Leukemia can either be acute or chronic, which is a categorization used to describe the speed of disease progression. Acute leukemia is when abnormal cells divide rapidly and the cancer progresses quickly; whereas in chronic leukemia the abnormal cells are slower to develop and symptoms may not appear for years.
Leukemia can be further classified by cell type and is either myelogenous or lymphocytic. Myelogenous leukemia develops in early myeloid cells. Normal myeloid cells develop into white blood cells, red blood cells and platelets. Normal lymphoid cells develop into certain types of white blood cells (lymphocytes and natural killer cells).
The four main types of leukemia include:
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CLL
Chronic lymphocytic leukemia (CLL) is the most common chronic leukemia in adults and more common in people >65
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ALL
Acute lymphocytic (or lymphoblastic) leukemia (ALL) can affect adults of any age, but is the most common type in children, teens and young adults up to 39 years old
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CML
Chronic myeloid (or myelogenous) leukemia (CML) is more common in adults >65
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AML
Acute myeloid (or myelogenous) leukemia (AML) is the most common type of acute leukemia in adults and more common in adults >65
Chronic lymphocytic leukemia (CLL) is a cancer of the lymphocytes, which is a type of white blood cell involved in the body’s immune system. CLL and small lymphocytic lymphoma (SLL) are the same cancer in that they differ only by the location of the cancer cells. There are different types of CLL based on whether the disease causes an overgrowth of B cells or T cells. Over 95% of people with CLL have the B cell type. In some people with CLL, the cancer grows and progresses slowly and it may take years for any symptoms to appear; whereas, in other patients, the cancer grows more rapidly. Over time, the leukemia cells may grow and spread to other parts of the body, including your lymph nodes, liver or spleen.
