The lymphatic system is one of the body's natural defenses against infection. It is a complex system made up of lymph organs, such as bone marrow, tonsils, the thymus and the spleen, and lymph nodes connected by a network of tiny lymphatic vessels. Lymph nodes are found mainly in the neck, armpit and groin. Their number varies from one part of the body to another. In some parts there are very few whereas, under your arm there may be between 20 and 50 nodes.

Circulating through the lymphatic vessels is a milky-looking fluid called lymph containing lymphocytes. Lymphocytes are white blood cells, an essential part of the body's defense against infection and disease. If, for example, you have a sore throat, you may notice that the lymph nodes in your neck become enlarged; this is a sign that your body is fighting the infection.

There are two main types of lymphocyte: 'B-cells' and 'T-cells'. All lymphocytes develop in the bone marrow from immature cells called stem cells. Lymphocytes which mature in the thymus gland (behind the breast bone) are called 'T-cells'. Other lymphocytes mature in the bone marrow or lymphatic organs and are called 'B-cells'.

What is Hodgkin's Disease?

Hodgkin's disease is a cancer of the lymphatic system. Also known as a lymphoma.

Hodgkin's disease, like other cancers, is a disease of the body's cells. Cells in different parts of the body work in different ways, but they all repair and reproduce themselves the same way. Normally, this division of cells takes place in an orderly and controlled manner, but if for some reason the process gets out of control, the cells continue to divide. There may be too many immature white blood cells in the blood or bone marrow, and a lump or tumor may develop in one or more groups of lymph nodes.

Lymphoma cells generally start to grow in lymph nodes (also called lymph glands), which are part of the lymphatic system. Usually Hodgkin's disease affects groups of lymph nodes in one area of the body. However, the lymphoma cells can sometimes spread through the lymphatic system to lymph nodes in other parts of the body. They go into the bloodstream, which may carry them to other organs. When the cells reach a new area they continue to divide and form a new tumor.

As there are lymph nodes and lymph vessels throughout the body, Hodgkin's disease can occur in any part of the body. The most common place for it to occur is in the lymph nodes in the neck. The next most common places are the lymph glands under the arms, in the chest, or in the groin or abdomen. It can also occur in organs. In some people, Hodgkin's disease will affect the liver, lungs or bone.

The treatment of Hodgkin's disease, even when it has spread to different areas of the body , is usually very successful. Most people can now be cured, or their disease can be controlled for many years.

A diagram showing the main groups of lymph nodes in the body.

Non-Hodgkin’s Lymphoma: There are more than 30 subtypes of lymphoma, consisting of 5 types of Hodgkin’s lymphoma (also known as Hodgkin’s disease) and over 25 types of non-Hodgkin’s lymphoma. Lymphoma is the most common blood cancer and the third most common childhood cancer.

What is Non-Hodgkin’s Lymphoma?
Non-Hodgkin’s lymphoma (NHL) is the most common cancer of the lymphatic system. Since the early 1970’s, incidence rates for non-Hodgkin’s lymphoma have nearly doubled. Over the 25-year period between 1973 and 1998, new cases of NHL seen each year escalated almost 83%, among the highest increases of any cancer. The overall five-year survival rate is only 56%. Of the nearly 500,000 Americans with lymphoma, 332,000 have this form. Each year, approximately 54,370 new cases of NHL will be diagnosed and 19,410 Americans will die from the disease.

NHL is not a single disease, but rather a group of several closely related cancers that affect the lymphatic system, which is part of the immune system.

NHL is broadly divided into two major groups: 'B-cell' lymphoma (which develops from abnormal B-lymphocytes, which is most common), and 'T-cell' lymphomas (which develop from abnormal T-lymphocytes). Lymphocytes are a type of white blood cell that helps the body fight infections. 'B' cells develop into plasma cells that produce antibodies to fight infections, while 'T'-cells attack foreign invaders (bacteria, viruses, cells, etc.) directly.

How does Non-Hodgkin’s Lymphomas develop?
NHL can start in the lymph nodes, in a specialized lymphatic organ such as the spleen, or in lymph tissue found in organs such as the stomach or intestines. Since lymphocytes (white blood cells) can circulate to all parts of the body through the lymphatic vessels and bloodstream, abnormal lymphocytes can reach any part of the body. Thus, NHL can start in or spread throughout the body in a similar fashion. While some NHLs are localized to one area, most are present in other parts of the body by the time the diagnosis is confirmed.

What are the warning signs?
While most people who have these complaints will not have lymphoma, anyone with persistent symptoms should be seen by a doctor to make sure that lymphoma is not present: chills, painless swelling of the lymph nodes, fever, night sweats, unexplained weight loss, lack of energy, and itching.

What are the risk factors?
The causes of lymphoma remain unknown, but immune system impairment and exposure to environmental carcinogens, pesticides, herbicides, viruses, and bacteria may play a role. There may be a higher risk for getting lymphoma in individuals:

How is Lymphoma treated?
While many effective treatment options exist, low grades of lymphoma usually recur—some people go in and out of remission for years. In certain patients with indolent disease, treatment may not be necessary until there are signs of progression. Response to treatment can change over time, what worked initially may be ineffective the next time, making it necessary to always keep abreast of the latest information on new or experimental treatment options.

However, 30% to 60% of patients with “aggressive” lymphoma can be cured. Although the “indolent” forms of lymphoma are not currently curable, the prognosis is still very good, and patients may live for 20 years or more. Many people treated for lymphoma will receive some form of chemotherapy, radiation therapy, biologic therapy, or a combination of these. Bone marrow or stem cell transplantation may sometimes be used. Surgery may be used under special circumstances, but is used primarily for diagnosis.