Non-Hodgkin's lymphoma is cancer of the lymphoid tissue, which includes the lymph nodes, spleen, and other organs of the immune system.

White blood cells called lymphocytes are found in lymph tissues. Most lymphomas start in a type of white blood cells called B lymphocytes, or B cells.

For most patients, the cause of this cancer is unknown. However, lymphomas may develop in people with weakened immune systems. For example, the risk of lymphoma increases after an organ transplant or in people with HIV infection.

Non-Hodgkin's lymphoma is classified according to how fast the cancer spreads. The cancer may be low grade, intermediate grade, or high grade. Burkitt's tumor is an example of a high-grade lymphoma. There are many different types of non-Hodgkin's lymphoma.

According to the American Cancer Society, a person has a 1 in 50 chance of developing non-Hodgkin's lymphoma. Most of the time, this cancer affects adults. However, children can get some forms of lymphoma. High-risk groups include those who have received an organ transplant or who have a weakened immune system (immunosuppression).

This type of cancer is more common in men than in women.

Non-Hodgkin's lymphoma can cause a variety of symptoms. Symptoms depend on what area of the body is affected by the cancer. Symptoms may include:

• Excessive sweating, especially while sleeping at night
• Fever
• Severe itchiness
• Swollen lymph nodes in the neck, underarms, groin, or other areas
• Unintentional weight loss

Coughing or shortness of breath may occur if the cancer affects the thymus gland or lymph nodes in the chest, which puts pressure on the windpipe (trachea) or other airways.

Some patients may have abdominal pain or swelling, which may lead to a loss of appetite, constipation, nausea, and vomiting.

If the cancer affects cells in the brain, the person may have a headache, concentration problems, personality changes, or seizures.

The doctor will perform a physical exam and check body areas with lymph nodes to feel if they are swollen. Tests to diagnose and stage non-Hodgkin's lymphoma include:

• Blood chemistry tests
• Bone marrow aspiration and biopsy
• CBC with white blood cell differential
• CT scans of the chest, abdomen and pelvis
• Lymph node biopsy
• PET (positron emission tomography) scan
• X-rays

Treatment depends on how quickly the cancer spreads, the stage of the cancer when you are first diagnosed, and any symptoms.

Chemotherapy is commonly used as the main form of treatment.

Another drug, called rituximab (Rituxan), is often used to treat non-Hodgkin's lymphoma. Rituxan is a form of immunotherapy. It targets a molecule on the surface of B-cells.

Radioimmunotherapy may be used in some cases. This involves linking a radioactive substance to an antibody that helps the immune system fight infection, and injecting the substance into the body.

In select cases, a stem cell or bone marrow transplant may be needed.

The stress of illness may be eased by joining a support group whose members share common experiences and problems.

See: Cancer - support group

Low-grade non-Hodgkin's lymphoma can't be cured with chemotherapy alone. However, the low-grade form of this cancer progresses slowly, and it may take more than 10 years before the disease gets worse.

Chemotherapy can help cure high-grade lymphoma. However, if the cancer does not respond to chemotherapy drugs, the disease can cause rapid death.

• Autoimmune hemolytic anemia
• Infection

Call your health care provider if you develop symptoms of this disorder.

If you have non-Hodgkin's lymphoma, call your health care provider if you experience persistent fever or other signs of infection.

Bierman P, Harris N, Armitage J. Non-Hodgkin's lymphomas. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 196.

National Comprehensive Cancer Network Clinical Practice Guidelines in Oncology: Non-Hodgkin's Lymphomas. National Comprehensive Cancer Network; 2009. Version 2.2009.