Lymphoma

Lymphoma (lim-FO-ma) is the name for a group of cancers that arise in the lymph nodes, which are part of the immune system. These cancers include Hodgkin's disease and non-Hodgkin's lymphoma.

What Is Lymphoma?

Lymphoma is a general term for a group of cancers that begin in the lymphatic system, the body system that includes the tissues and organs that make, store, and carry the white blood cells that fight infections and other diseases. This system includes the bone marrow ^* , spleen ^* , and hundreds of bean-sized lymph nodes ^* throughout the body. Lymphoma results when white blood cells, or lymphocytes (LIM-fo-sites), undergo changes and start to multiply out of control. Eventually, the cells crowd out healthy cells and create tumors ^* . Lymphoma can occur in a single lymph node, a group of lymph nodes, or in other parts of the lymphatic system, such as the spleen or bone marrow. Eventually, it may spread to almost any part of the body.

Lymphoma is divided into two main types: Hodgkin's disease, named after Dr. Thomas Hodgkin, who discovered it in 1832, and non-Hodgkin's lymphoma. The cancer cells in Hodgkin's disease look different under a microscope than do the cells in non-Hodgkin's lymphoma. However, both cancers make a person sick in the same way. Some types of lymphoma are among the most common childhood cancers. Nevertheless, most cases of lymphoma occur in adults.

What Causes Lymphoma?

No one knows exactly what causes lymphoma. It is not contagious, like a cold or chickenpox. People with other kinds of cancer sometimes have what are known as risk factors. A risk factor is anything that increases a person's chances of getting a disease. Having AIDS ^* or an autoimmune disease ^* increases the risk for lymphoma. However, most people with lymphoma have no known risk factors.

Scientists recently have made great progress in understanding how certain changes in DNA may cause normal lymphocytes to become lymph-omas. DNA is material that people inherit from their parents that carries the instructions for everything the cells do. Just as people get bumps and scrapes during their lifetimes, the genes ^* , which are part of DNA, also suffer different kinds of damage or malfunction. When that happens, a cell may receive wrong signals that cause it to grow out of control and form a tumor.

In addition, certain viruses appear to cause changes in genes that can lead to lymphoma. Epstein-Barr virus ^* can cause lymphoma in people with weakened immune systems ^* . In people with healthy immune systems, the same virus has been linked to a form of the disease called Burkitt's lymphoma. This illness occurs in children and adults in Central Africa, but is rare in the United States. A virus called HTLV-1 ^* causes a kind of lymphoma seen almost only in certain geographical areas, particularly Japan, the Caribbean, and the southeast United States. In most cases, however, doctors simply have no idea why lymphoma develops.

What Are the Symptoms of Lymphoma?

Some people with lymphoma have early symptoms that cause them to go to the doctor. Others, however, may have no symptoms at all, or they may mistake their symptoms for the flu or another ordinary illness. This is because the body responds to lymphoma as though it were an infection. For example, Jacqueline Kennedy Onassis, the widow of President John F. Kennedy, was diagnosed with lymphoma after she went to the doctor thinking she had the flu. John Cullen, a hockey player for the Tampa Bay Lightning, experienced his first symptom as a pain in his chest after a game. Other common symptoms of lymphoma are painless swellings in the neck, armpit, or groin; night sweats; and tiredness. In addition, the same physical reaction that causes itchiness in allergic reactions can cause widespread itching in lymphoma.

This drawing shows the lymphatic system, which includes a network of tiny tubes that branch, like blood vessels, it tissues throughout the body. Lymph nodes are located along this network.

How Is Lymphoma Diagnosed?

If lymphoma is suspected, the doctor can order various medical tests, including imaging studies to allow the doctor to see inside the body. Because many of the symptoms of lymphoma can be caused by non-cancerous problems such as infections, the only way to be sure that a person has lymphoma is to do a biopsy (BY-op-see). This procedure involves removing a sample of tissue from a lymph node, or sometimes even an entire node, for examination under a microscope.

How Is Lymphoma Treated?

Once the doctor knows for sure that a patient has lymphoma, the next step is to do something called staging. This means seeing whether the cancer has spread, and if so, how far. Staging is the most important step in deciding what kind of treatment a person with lymphoma will get and what the outlook for survival is. The systems used to stage Hodgkin's disease and non-Hodgkin's lymphoma are different, but the goal of both is to decide the best treatment for the patient.

Early stage non-Hodgkin's lymphoma that has not spread is usually treated with radiation therapy, which uses high-energy waves to damage and destroy cancer cells. If the disease is widespread, it will probably require chemotherapy (kee-mo-THER-a-pee), which uses anticancer drugs that can reach everywhere in the body to fight cancer cells. Chemo-therapy drugs are given either through a vein in the arm or as pills. Sometimes chemotherapy is combined with radiation. Hodgkin's disease also is treated with radiation, chemotherapy, or both.

Both chemotherapy and radiation can have side effects, because treatments that kill cancer cells can affect healthy cells, too. The most common side effects of chemotherapy are nausea (feeling sick to the stomach), vomiting, hair loss, and tiredness. Nausea and vomiting can be prevented with medication, and, fortunately, most of these side effects go away after the treatment is completed.

Is It Possible to Prevent Lymphoma?

Unlike many other kinds of cancer, there are no known factors related to lifestyle, such as exposure to sunlight or specific eating habits, that a person could change in the hope of lowering the risk of getting lymphoma. However, preventing HIV (AIDS virus) infection would prevent many cases of non-Hodgkin's lymphoma.

Will Treatment for Lymphoma Change in the Future?

Today researchers are studying how normal lymphocytes develop into cancer cells. This information may be used one day in gene therapy ^* to replace abnormal genes with normal ones and allow cells to grow normally again. This same knowledge also is being used to try to detect lym-phoma earlier and to test how completely lymphoma has been destroyed by treatment.

Lymphoma cells sometimes become resistant to chemotherapy. This means that the cancer cells are able to change so that the drugs are no longer effective. Drugs are being studied that can interfere with this resistance, thus making chemotherapy more effective. Treatments that help the patient's immune system recognize and destroy the lymphoma cells also are being investigated.

Living with Lymphoma

Because treatment of both non-Hodgkin's lymphoma and Hodgkin's disease usually involves chemotherapy and radiation, one of the hardest parts of living with lymphoma is coping with treatment. Many side effects of chemotherapy and radiation are short-term and will go away when treatment stops. However, other side effects are long-term. For example, treatment may affect a person's ability to have children, or it may trigger the development of a different lymphoma many years later.

Follow-up care may continue for years or even decades. Aside from doctor's visits, though, once all signs of cancer are gone, people can go back to doing whatever they did before they got lymphoma. Most children with childhood lymphoma will survive it, and they can expect to lead normal lives as adults.