Leukemia is the tenth most common cancer constituting about 3.5% of all cancers in the United States (US).
Leukemia is divided into four main types:
CLL is the most common leukemia in the US and western hemisphere accounting for about one-quarter of all leukemia cases. The overall incidence and mortality rate of CLL has been slightly declining during the last decade.
CLL more commonly affects older age individuals with highest incidence observed in individuals aged between 65 to 74 years. The incidence rate of CLL is slightly higher in males than in females.
The blood is a connective tissue consisting of a liquid extracellular matrix (the plasma) and suspended formed elements (comprising blood cells and cell fragments). The 3 main components of formed elements include red blood cells (RBCs), white blood cells (WBCs) and platelets.
The WBCs are further divided into various subtypes based on their appearance under the microscope (with the application of different staining): neutrophils, basophils, eosinophils, monocytes, and lymphocytes (T-cells, B-cells, and natural killer cells). Each type of blood cell has a distinct function and is produced from pluripotent stem cell in the red bone marrow by a process called hemopoiesis.
CLL is a disorder in which abnormal B lymphocytes (leukemia cells in CLL look like mature B lymphocytes) start dividing without control. The abnormal B lymphocytes slowly get crowded in the red bone marrow and peripheral blood causing a reduction in the number of normal RBCs, WBCs, and platelets.
The CLL cells can spread to different organs like liver, spleen, and lymph nodes. Pathologically, CLL is defined as the presence of >/=5 x 10^9/L malignant monoclonal B cells in the blood. CLL cells express the B-cell markers CD19, CD20, CD21, CD23; and T-cell marker CD5.
Following are certain lymphoproliferative disorders that may look similar to CLL and required to be differentiated from CLL:
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Several epidemiological studies have revealed a few risk factors that can predispose CLL. Following is the list of such risk factors:
Following are some common signs and symptoms of CLL:
If a person is suspected to have CLL, some investigations are required to confirm the diagnosis of the disease. Further, these investigations can help in determining the extent of disease and help in selecting an appropriate treatment approach.
Following are some commonly used diagnostic tools for CLL:
Apart from establishing the diagnosis of CLL, investigational tests play an important role in assessing the response to treatment. Following are various terms used to indicate the different responses to treatment:
The staging system is used to describe the severity of CLL based on various clinical parameters such as lymphocytosis; involvement of lymph nodes; enlargement of the spleen and/or liver; hemoglobin level; and platelets count. Staging helps to determine the disease prognosis, and thus, to select an appropriate treatment strategy.
“Rai” and “Binet” are the two most commonly used staging system for CLL by the medical community. The Rai system is mostly used in the US and the Binet system is mainly used in Europe. The Rai system assigns 5 stages (from 0 to IV) to the disease while the Binet system assigns 3 stages (A, B, and C) to the disease.
Following table describes the characteristics of CLL according to different stages and different systems:
|RAI STAGE||RISK GROUP||DESCRIPTION|
|0||Low||Lymphocytosis (>/=5*10^9/L leukemia cells in the blood and >40% leukemia cells in the bone marrow); no enlargement of the lymph nodes, spleen, or liver; RBCs and platelet counts are near normal|
|I||Intermediate||Lymphocytosis with enlarged lymph node(s)|
|II||Intermediate||Lymphocytosis with splenomegaly and/or hepatomegaly|
|III||High||Lymphocytosis with hemoglobin <11.0 g/dL or hematocrit <33%|
|IV||High||Lymphocytosis with platelets <100,000/microliter|
|A||Hemoglobin >/=10 g/dL, Platelets >/=100,000/mm^3 and <3 enlarged nodal areas|
|B||Hemoglobin >/=10 g/dL, Platelets >/=100,000/mm^3 and >/=3 enlarged nodal areas|
|C||Hemoglobin <10 g/dL and/or Platelets <100,000/mm^3|
Many other factors have been identified in different clinical research studies, which can predict the outcome of CLL. These factors are not included in the staging system but are taken into account before starting the treatment for CLL. Following are examples of such prognostic factors:
Adverse prognostic factors: Examples of adverse prognostic factors include
The treatment of CLL depends on many factors, including but not limited to, patient’s age, overall health or comorbidities, stage/risk group, immunophenotypic/cytogenetic abnormality involved, etc.
Decision for whether to treat the patient or to observe is taken on the basis of – disease related symptoms (fever, night sweats, weight loss, etc), threatened end organ function, progressive bulky disease, progressive anemia or thrombocytopenia, lymphocyte doubling time, etc. If none is present, patient may be observed closely, but the final decision is taken after clinical assessment of the patient by an oncologist.
|CLL without del(17p) or TP53 mutation||
Chemoimmunotherapy (chemotherapy plus monoclonal antibody) or targeted therapy is considered as the preferred treatment for both elderly and young patients with significant comorbidities.
In patients <65 years of age and without significant comorbidities, Chemoimmunotherapy is considered as the preferred treatment approach.
|CLL with del(17p) or TP53 mutation||Targeted therapy is considered the preferred treatment for both elderly and young patients with or without any significant comorbidities.|
Following is the brief description of various treatment types employed for CLL:
It is very important to assess the benefits of each treatment option versus the possible risks and side effects before making a treatment decision. Sometimes patient’s choice and health condition are also important to make a treatment choice.
Following are the goals of treating Chronic lymphocytic leukemia:
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