Chronic lymphocytic leukemia (CLL) is a malignant disease of the blood (leukemia), characterized by the proliferation of lymphocytes (type of white blood cells made in the bone marrow) which places it in the category of chronic lymphoid malignancies. This is the most common leukemia, affecting preferentially the elderly over 50 years old. Apart from a few familial cases, there are no known factors favoring the onset of the disease: environmental, genetic or infectious. This condition is incurable so far, but the prognosis is extremely variable from one patient to another. For 60% of patients it is not necessary to start treatment at initial diagnosis of the disease due to its slow scalability.
Chronic lymphocytic leukemia is defined by the monoclonal proliferation of a population of mature B lymphocytes. These cells will gradually invade the blood, lymphoid organs, and the bone marrow. But the cellular mechanisms inducing lymphocyte proliferation are not completely understood.
Causes of Chronic Lymphocytic Leukemia
In chronic lymphocytic leukemia, the male / female ratio is 2 /1 and the peak frequency is around the age of 65. CLL is rare before age 40, and affects a patient over 50 years in 90% of cases. This is the most common chronic leukemia in Western countries; the incidence is estimated at 3.5 new cases per 100,000 people in the United States. It is rarer in the Far East.
Chronic lymphocytic leukemia appears to be a familial predisposition with a three -fold increased risk if a sibling is affected by the tumor. It does not seem to have environmental triggers with the exception of exposure to defoliant, a chemical that is sprayed on plants to cause their leaves fall off. Similarly, the potentiating role of irradiation remains controversial. Repeated infections, especially in the lung however, appear to be a risk factor for the disease, probably due to an iterative stimulation of the immune system.
Symptoms of Chronic Lymphocytic Leukemia
In about one third of chronic lymphocytic leukemia cases, there are no clinical signs of the disease at the beginning. The disease is often discovered during blood test such as complete blood count (CBC). The most common clinical signs or symptoms tend to be discovered by the patient himself or during an examination of a superficial lymphadenopathy (disease of the lymph nodes) or splenomegaly (increased spleen volume). More rarely, the diagnosis is straightforward to an infectious complication or an autoimmune disorder.
The presence of fever, night sweats or poor general condition can be a warning sign indicating that the patient must immediately seek medical care to confirm or rule out underlying infection, transformation of CLL in high-grade lymphoma (Richter’s transformation, or Richter’s syndrome) or cancer related to other organs.