Chronic Lymphocytic Leukemia (CLL) and Small Lymphocytic Lymphoma (SLL) are the same disease with slightly different manifestations. Where the cancerous cells gather determines whether it is called CLL or SLL. When the cancer cells are primarily found in the lymph nodes, lima bean shaped structures of the lymphatic system (a system primarily of tiny vessels found in the body), it is called SLL. When most of the cancer cells are in the bloodstream and the bone marrow, it is called CLL.
CLL is essentially a cancer of the B-lymphocytes. Scientists used to say there were both T-cell CLL and B-cell CLL. However, since 2001, scientists now agree that the usual CLL is a cancer of the B-cells.
Leukemic cells develop because of a change that takes place in the cell’s DNA. Normal (non-cancerous) cells go through stages of growth, division and death. In cancer cells, changes in the DNA (mutations) create cells that keep dividing and/or avoid early or usual cell death (apoptosis). Thus, CLL is usually a disease of accumulation of long lived cells in the body, including the blood, bone marrow, lymph nodes or spleen.
There are three types of blood elements: red blood cells, white blood cells and platelets. Each starts out from a single cell type called a stem cell. The human body maintains a fresh supply of cells in the bloodstream by making stem cells in the bone marrow. These stem cells replicate or mature into red blood cells, white blood cells, or platelets depending on the body’s needs at any given time.
White blood cells are the cells in the body that fight infections. Neutrophils and lymphocytes are two of the major subtypes of white blood cells. Lymphocytes include the following:
- T-cell lymphocytes - Help the body fight viral, fungal or tuberculous infections and destroy abnormal (or cancerous cells).
- B-cell lymphocytes - Make antibodies that can attack the target. Antibodies attach themselves to bacteria and other organisms and alert other immune system cells, such as neutrophils, to their presence in the body.
- Natural Killer cells (NK-cells) - Kill off virally infected cells and other cancer cells.
How the Immune System Works
The immune system consists of a network of cells, tissues and organs that defend the body against “foreign” invaders (such as bacteria or viruses) or abnormal cells. A person’s ability to survive exposure to both external invaders and internal cell mutations (abnormalities) largely depends on the immune system. The immune system is the body’s first defense against disease. It is made up of highly specialized cells and a circulatory system separate from blood vessels called the lymphatic system. The specialized cells and the lymphatic system work together to rid the body of foreign invaders or abnormal cells before they can harm the body. These invading organisms and abnormal or cancerous cells are generally detected by the immune system through antigens (proteins that are located on the surface of all cells). Special receptors located on the immune cells lock on to these antigens. And just as a lock will only close with the right key, an antigen will only lock with a specific cell from the immune system. When an antigen and an immune cell lock together, the immune response begins, and the body acts to destroy, remove or wall-off the foreign invaders or abnormal cells.
In CLL/SLL, the risk of infection is heightened due to a compromised immune system from the cancer and/or its treatment. An estimated 75 percent of CLL/SLL patients will have hypogammaglobulinemia, a condition in which the level of immunoglobulins (antibodies) in the blood is low (hypo). This condition increases the risk for infection, despite the fact that CLL patients have the normal amount of infection-fighting B-cells. One reason may be that the body’s T-cells, which help the B-cells make antibodies to fight off infection, are not working properly.
CLL/SLL patients also have defective activation of a group of blood proteins called the complement system, which help fight common bacteria to which these patients are susceptible. To ward off infections, it is best to stay up-to-date on vaccines for pneumonia and influenza, although they may not work as well because of the impaired immune system resulting from the disease. CLL/SLL patients should also avoid live vaccines (e.g., chicken pox vaccine).
In addition, T-cell dysfunction may also be responsible for altering the immune system, causing it to attack healthy red blood cells (autoimmune hemolytic anemia) and platelets (thrombocytopenia). This can result in fatigue, shortness of breath and bleeding disorders.
How the Lymphatic System Works
The lymphatic system is one of the most important parts of the immune system because it protects the body from disease and infection. The lymphatic system is a circulatory system made up of a series of thin tubes called lymph vessels that branch like blood vessels into all tissues of the body. Lymph vessels carry lymph, a transparent fluid that contains white blood cells called lymphocytes. Within this vast network of vessels are groups of small, bean-shaped organs called lymph nodes. Thousands of lymph nodes are found throughout the body, including the elbows, neck, under the arms and groin. Lymph flows through lymph nodes and specialized lymph tissues such as the spleen, tonsils, bone marrow and thymus gland.
Lymph nodes filter lymph fluid, removing bacteria, viruses and other foreign substances from the body. If a large number of bacteria are filtered through a node or series of nodes, they may swell and become tender to the touch. For example, if a person has a sore throat, the lymph nodes under their jaw and in their neck may swell. Most swollen nodes are a reaction to infection and are not cancerous.
Talking to Your Healthcare Team
Many people receive a diagnosis of CLL/SLL from their general practitioners or local oncologist. While CLL/SLL has been considered an indolent (slow-growing) or benign illness, it in fact can be quite unpredictable and become quite aggressive. For this reason, finding a hematologist/oncologist (someone who specializes in treating blood cancers) is critical. Very often, patients travel to cancer centers known for their expertise in treating lymphoma for second opinions and return home for treatment.
When talking to your physician and other members of your healthcare team, consider the following:
- Ask questions if you do not understand something
- Tell your doctor if you have concerns
- Do be informed – but always consider the credibility of the information source so you can make informed decisions
- Bring someone along to your appointments and take notes
- Consider the side effects you are willing to accept to maintain the best possible quality of life throughout treatment
Taking control of your care requires you to learn about CLL/SLL, from this website and other sources, speak to the experts and make informed decisions about tests and treatment options. You should be your own best advocate.