Non-Hodgkin's lymphoma is cancer that originates in your lymphatic system, the disease-fighting network spread throughout your body. In non-Hodgkin's lymphoma, tumors develop from white blood cells (lymphocytes). These tumors can occur at different locations in your body. There are more than 30 types of non-Hodgkin's lymphoma.

Non-Hodgkin's lymphoma is more than seven times as common as the other general type of lymphoma — Hodgkin's disease. Non-Hodgkin's lymphoma has been one of the most rapidly increasing types of cancer in the United States, having more than doubled in incidence since the 1970s.

The good news is that although the incidence has increased, so has the survival rate. As with other cancers, the earlier you receive a diagnosis, the greater your chance for a successful treatment of non-Hodgkin's lymphoma.

Swollen, painless lymph nodes in your neck, armpit or groin areas are often the only sign of non-Hodgkin's lymphoma in its early stages. Other signs and symptoms may include:

• Fever
• Night sweats
• Fatigue
• Weight loss
• Abdominal pain or swelling

Normally, your white blood cells (lymphocytes) go through a predictable life cycle. Old lymphocytes die, and your body creates new ones to replace them. But in non-Hodgkin's lymphoma, your body produces abnormal lymphocytes that continue to divide and grow uncontrollably. This oversupply of lymphocytes crowds into your lymph nodes, causing them to swell.

Doctors don't know what exactly causes non-Hodgkin's lymphoma. But researchers believe that activation of certain abnormal genes may be involved in the development of all cancers, including lymphomas.

Lymphocytes exist either as B cells or T cells. B cells fight infection by producing plasma cells, which in turn produce antibodies that neutralize foreign invaders. T cells are involved in killing foreign invaders directly. About 85 percent of non-Hodgkin's lymphomas occur in B cells. The rest arise in T cells.

Non-Hodgkin's lymphoma generally involves the presence of cancerous cells in your lymph nodes, but the disease can also spread to other parts of your lymphatic system. These include the lymphatic vessels, tonsils, adenoids, spleen, thymus and bone marrow. Occasionally, non-Hodgkin's lymphoma involves organs outside of the lymphatic system.

In most cases, people diagnosed with non-Hodgkin's lymphoma don't have any obvious risk factors, and many people who have risk factors for the disease never develop it. Some factors that may contribute to your risk of non-Hodgkin's lymphoma include:

• Age. Non-Hodgkin's lymphoma can occur at any age, but the risk increases with age. It's most common in people in their 60s.
• Immunosuppression. If you've had an organ transplant, you're more susceptible because immunosuppressive therapy has impaired your immune mechanisms.
• Infection. A number of infections appear to increase the risk of non-Hodgkin's lymphoma. Having AIDS, in which your immune system is progressively weakened, also places you at higher risk. In Africa, infection with the parasite that causes malaria or the Epstein-Barr virus appears to raise the risk of a particular type of non-Hodgkin's lymphoma, called Burkitt's lymphoma. An infection with the bacterium Helicobacter pylori, which is known to cause ulcers, can cause an immune system response that raises your risk of non-Hodgkin's lymphoma, particularly in the stomach.
• Chemicals. Certain chemicals, such as those used to kill insects and weeds, may increase your risk of developing non-Hodgkin's lymphoma. Previous studies had suggested that long-term use of dark-colored hair dyes might be linked to an increased risk of the disease, but a review in the May 25, 2005, issue of the Journal of the American Medical Association found only a weak association between hair-dye use and non-Hodgkin's lymphoma. Since the evidence is inconclusive, more research is needed. However, the chemicals used in hair dyes have changed since the 1980s, so any possible risk that may have existed then may be even smaller now.

If you have persistent swelling of your lymph nodes, have a persistent fever, have lost weight or regularly experience night sweats and fatigue, see your doctor to determine the underlying cause. The earlier non-Hodgkin's lymphoma is diagnosed, the greater your chances for successful treatment.

Your doctor may use these procedures to help diagnose non-Hodgkin's lymphoma:

• Physical examination. Your doctor may examine not only your swollen lymph nodes but also your other lymph nodes to determine their size and consistency.
• Blood and urine tests. Usually, having swollen lymph nodes means you're fighting an infection. Blood and urine tests may help your doctor rule out an infection or other disease.
• Imaging techniques. An X-ray or computerized tomography (CT) scan of your chest, neck, abdomen and pelvis may detect the presence and size of tumors. Doctors are also increasingly using positron emission tomography (PET) scanning to detect cancer. For this test, a small amount of a radioactive tracer is injected into your body. This tracer is then absorbed by the tissues in your body. Tumors are typically more metabolically active than other tissues, so they absorb more of the tracer.
• Lymph node biopsy. Taking a sample of lymph node tissue for examination in the laboratory may reveal whether you have non-Hodgkin's lymphoma and, if so, which type. This procedure may show the lymphoma to be growing slowly (low grade), growing at a moderate rate (intermediate grade) or growing rapidly (high grade). Knowing the growth rate of your tumor can help determine which treatment is best for you.
• Bone marrow biopsy. To find out whether the disease has spread, your doctor may request a biopsy of your bone marrow. This involves inserting a needle into your pelvic bones to obtain a sample of bone marrow.

Classifying the condition
Doctors classify non-Hodgkin's disease into about 30 types. Besides the differentiation between B cell and T cell types of the disease, classification is based on several other factors. These include:

• Microscopic appearance
• Cellular genetic changes
• Cell size
• Staining patterns with specific antibody stains
• How the cancer cells group together
• How fast the cancer grows

Doctors also assign a stage (I through IV) to the disease, based on the number of tumors and how widely the tumors have spread.

Several factors affect the choice of treatment, including the type and stage of your lymphoma, your age, and your overall medical condition. The main treatment options include:

• Chemotherapy. Doctors use a combination of drugs — given orally or by injection — against fast-growing cancer cells. This treatment is used for intermediate- and high-grade lymphomas and advanced stages of the low-grade lymphomas. A single drug may be used if you have a low-grade type of the disease.
• Radiation. High doses of radiation kill cancerous cells and shrink tumors. This treatment is for early stages of low-grade lymphomas. Sometimes, it's used along with chemotherapy on intermediate-grade tumors or to treat specific sites, such as the brain.
• Stem-cell transplantation. Lymphomas tend to be sensitive to chemotherapy. However, if lymphoma recurs, higher doses of chemotherapy may be necessary to treat the disease. The amount of chemotherapy that can be given is limited because of the damage chemotherapy does to your bone marrow. In order to avoid this serious side effect, healthy stem cells — those capable of producing new cells — are taken from your blood or bone marrow and frozen. After you undergo very high doses of chemotherapy to kill the lymphoma, the healthy stem cells are thawed and injected back into your body. This treatment is used primarily to treat intermediate- or high-grade lymphomas that relapse after initial, successful treatment.
• Observation. If your lymphoma appears to be slow growing, a wait and see approach may be an option. Slowly growing lymphomas with few symptoms may not require treatment for a year or more.
• Biologic therapy. Rituximab (Rituxan) is the only form of stand-alone biologic therapy approved by the Food and Drug Administration (FDA) for the treatment of B-cell non-Hodgkin's lymphoma. Rituximab is a type of monoclonal antibody that helps the immune system specifically target and destroy cancer cells. Rituximab is frequently used in combination with chemotherapy. It is also sometimes given in tandem with radioimmunotherapy.
• Radioimmunotherapy. The newest form of treatment for the treatment of non-Hodgkin's lymphoma is radioimmunotherapy. Two radioimmunotherapy drugs — ibritumomab (Zevalin) and tositumomab (Bexxar) — have received FDA approval. Radioimmunotherapy uses monoclonal antibodies combined with radioactive isotopes. The antibodies attach themselves to the cancer cells, while the added radiation helps destroy the cancer cells. Radioimmunotherapy is generally well tolerated; however, serious side effects, including reduced blood cell counts, hemorrhage and life-threatening infections, are possible with these medications. That's why the FDA has approved their use only after other treatments have failed.

A diagnosis of cancer can be extremely challenging. Remember that no matter what your concerns or prognosis, you're not alone. These strategies and resources may make dealing with cancer easier:

• Know what to expect. Find out everything you can about your cancer — the type, stage, your treatment options and their side effects. The more you know, the more active you can be in your own care. In addition to talking with your doctor, look for information in your local library and on the Internet. The National Cancer Institute will answer questions from the public. You can reach the institute at (800) 422-6237. Or contact the American Cancer Society (ACS) at (800) 227-2345.
• Be proactive. Although you may feel tired and discouraged, don't let others — including your family or your doctor — make important decisions for you. It's vital to take an active role in your treatment.
• Maintain a strong support system. Having a support system and a positive attitude can help you cope with any issues, pain and anxieties that might occur. Although friends and family can be your best allies, they sometimes may have trouble dealing with your illness. If so, the concern and understanding of a formal support group or others coping with cancer can be especially helpful. Although support groups aren't for everyone, they can be a good source for practical information. You may also find you develop deep and lasting bonds with people who are going through the same things you are.
• Set reasonable goals. Having goals helps you feel in control and can give you a sense of purpose. But don't choose goals you can't possibly reach. You may not be able work a 40-hour week, for example, but you may be able to work at least part time. In fact, many people find that continuing to work can be helpful.
• Take time for yourself. Eating well, relaxing and getting enough rest can help combat the stress and fatigue of cancer. Also, plan ahead for the downtimes when you may need to rest more or limit what you do.
• Stay active. Receiving a diagnosis of cancer doesn't mean you have to stop doing the things you enjoy or normally do. For the most part, if you feel well enough to do something, go ahead and do it. Stay involved as much as you can.
• Look for a connection to something beyond yourself. Having a strong faith or a sense of something greater than yourself may help you cope with having cancer. It may also help you maintain a more positive attitude as you face the challenge of cancer.