Anemia can cause profound fatigue in a person with CLL.
Chronic lymphocytic leukemia, a slow-moving form of cancer caused by overproduction of a specific kind of white blood cell, is the most common type of adult leukemia in the Western world. Due to CLL's slowly progressive nature, many people remain symptom-free for many years. As abnormal white blood cells accumulate, fatigue, shortness of breath, weight loss and other symptoms may occur. Anemia -- a deficit of healthy red blood cells in your circulation -- is a common complication in people with CLL, but its cause is not always clear.
Bone Marrow Replacement
CLL develops when the maturation of lymphocytes in your bone marrow is interrupted. In healthy people, a lymphocyte begins its life as a stem cell and goes through several stages of development that determine whether it will be a T cell, B cell or natural killer cell, each of which serves a role in the immune system. Once mature, a lymphocyte has a predetermined lifespan, after which it dies and is replaced.
In CLL, mutations in your stem cells prevent them from maturing properly, so they never вЂњlearnвЂќ their proper functions. In addition, these abnormal lymphocytes live far longer than normal, so they begin to accumulate in your bone marrow and elsewhere in your body. Eventually, the stem cells that produce your red blood cells are crowded out of your bone marrow, resulting in decreased red blood cell production and anemia.
Suppressed Red Cell Production
Bone marrow replacement is not the only cause of anemia in people with CLL. According to a study published in the July 2009 issue of вЂњActa Haematologica,вЂќ CLL patients who are anemic tend to have higher levels of tumor necrosis factor in their bloodstream than non-anemic CLL patients. Tumor necrosis factor -- an inflammatory substance produced by immune cells -- disrupts the initial stages of red blood cell production in your bone marrow. So, even when there are stem cells capable of making red blood cells in your marrow, they may not be able to perform their job due to suppression by tumor necrosis factor.
Red Cell Destruction
In addition to bone marrow replacement and suppression by tumor necrosis factor, anemia in people with CLL may stem from destruction of red blood cells after they have reached the circulation. According to a May 2011 review in вЂњHaemtologica,вЂќ the abnormal lymphocytes that characterize CLL are capable of producing antibodies that target a person's own tissues, including the red blood cells. Approximately 1 in 14 people with CLL will develop an autoimmune hemolytic anemia -- destruction of red blood cells by self-targeting antibodies -- at some point during their disease.
Although many people with CLL survive for prolonged periods without chemotherapy, those who do undergo treatment may develop anemia as a result of their medications. The drugs used to treat leukemia suppress cellular multiplication, an effect that is necessary to reduce the numbers of abnormal cells but may spill over to affect normal cells. Cyclophosphamide (Cytoxan), fludarabine (Fludara) and rituximab (Rituxan), which are often used in combination for treating CLL, can all cause anemia. When these medications are administered together, the incidence of drug-induced anemia may be as high as 24 percent.
Anemia is a principal cause of decreased quality of life and may shorten survival in people with CLL. Chemotherapy-induced anemia is often addressed with medications that stimulate red blood cell production, such as erythropoietin (Epogen, Procrit). Those with autoimmune hemolytic anemia may respond to corticosteroids or other immune-suppressing drugs or agents that block tumor necrosis factor, such as rituximab. Removal of the spleen may also help correct autoimmune anemia. People whose anemia is due to bone marrow replacement may benefit from transfusion. Your doctor will determine the best treatment based on the cause of your anemia.