Lymphoma describes any cancer that develops within the lymphatic system. In order to understand lymphoma, it is necessary to first develop an understanding of cancer in general, as well as the function of the lymphatic system in the body.
Cells make up every part of the human body: skin, hair, nails, lymph nodes, blood and body organs. Cancer cells are descendants of a single normal cell in which genetic errors, or mutations, have occurred. In cells, genetic errors occur in the basic building blocks of DNA called genes. These errors may occur spontaneously or randomly when cells divide, or they may present themselves as a result of exposure to environmental toxins (carcinogens). Cancer occurs when these abnormal cells continue to grow at an uncontrolled rate. As these abnormal cells divide, they can eventually form a solid mass called a tumour. A malignant (cancerous) tumour will continue to grow at an uncontrolled rate and may eventually harm other areas of the body.
Most of the time, your body will react and correct the problem without you ever knowing. Cells will detect and correct errors, or other genes will become activated and cause the mutated cell to die. The immune system will also recognize damaged cells and kill them before tumours can form and cause problems. Because of all these factors, cancers are not thought to be the result of a single event. A combination of negative events and missed opportunities are required for cancers to form.
The lymphatic system is one of the most important parts of the immune system, protecting the body from disease and infection. It is made up of a series of thin tubes called lymph vessels that branch into all parts of the body carrying lymph, a watery fluid that contains lymphocytes.
The lymphatic system
Lymphocytes are a type of white blood cell that help the body fight infections. They develop in the thymus and bone marrow and are carried throughout the body by means of the bloodstream and lymphatic system.
There are two types of lymphocytes: B-lymphocytes and T-lymphocytes. B-lymphocytes develop into cells (called plasma cells) that make specific substances (called antibodies) that circulate in the blood and react with toxins, bacteria, and some cancer cells. The body can then identify and remove these unwanted substances.
However, some invaders can evade B-lymphocytes by growing inside the body’s cells. That is where T-lymphocytes come in. They sense when the body’s cells have become infected and destroy them directly. T-lymphocytes help the body fight viral infections and destroy abnormal or cancerous cells.
After an invader has been destroyed, surviving B-lymphocytes and T-lymphocytes develop into specialized memory cells that remain on watch in the lymph nodes, poised to attack if a certain antigen is encountered again. These special memory cells can be thought of as guards that are always on the lookout to prevent specific invaders from controlling the body.
Organs (other than lymph nodes) also considered part of the lymphatic system include:
A lymph node
Within the vast network of lymph vessels are groups of small, bean-shaped organs called lymph nodes. Lymph nodes act as the filter for the lymph fluid and lymphocytes, removing bacteria, viruses and other foreign substances. Hundreds of nodes are found in almost all places in the body, including the elbows, groin, neck, and armpits.
If a large number of bacteria are filtered though a node or series of nodes, like when you have a throat infection, they may swell and become tender to the touch. Most swollen nodes are just that—the immune system’s reaction to infection; not cancer.
Cancer occurs when abnormal cells cannot be controlled and continue to grow and multiply.
Lymphoma is a type of cancer that can appear when an error occurs in the way a lymphocyte is produced. In lymphoma a tumour develops because of uncontrolled growth of abnormal lymphocytes. Lymphoma encompasses a variety of cancers specific to the lymphatic system, an important network of glands and vessels that make up the body’s immune system, our main line of defense against disease. There are two main categories of lymphoma: Hodgkin’s and non-Hodgkin’s (NHL).
The lymphatic system manufactures and circulates lymph throughout the body. Lymph is a clear, watery fluid that contains lymphocytes, white blood cells that fight infection and disease. Along the network are bean-shaped organs called lymph nodes or glands. The nodes are responsible for the manufacture and storage of these infection-fighting cells. Lymph nodes are clustered in the neck, armpits, in the groin and abdomen and may swell and become tender when the body is fighting infection (such as occurs in mononucelosis or strep throat).
When lymphoma occurs, some of the cells in the lymphatic system grow abnormally and out of control. Eventually, they may form a tumour that continues to grow as the cancerous cells reproduce. If all the cells are the same, they are called malignant or cancerous, because they will continue to grow and eventually harm the body’s systems. Because there is lymph tissue throughout the body, the cancer cells may spread to other organs, or even into the bone.
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