Non-Hodgkin's lymphoma (also called NHL) is cancer that begins in the lymphatic system. It starts when a lymphocyte (a B cell or T cell) becomes abnormal. Usually, non-Hodgkin's lymphoma starts in a B cell in a lymph node. The abnormal cell divides to make copies of itself. The new cells divide again and again, making more and more abnormal cells. The abnormal cells are cancer cells. They do not die when they should. They do not protect the body from infections or other diseases. Also, the cancer cells can spread to nearly any other part of the body.
Doctors can seldom explain why one person develops non-Hodgkin's lymphoma and another does not. But research shows that certain risk factors increase the chance that a person will develop this disease. In general, the risk factors for non-Hodgkin's lymphoma include the following:
• Weak immune system: Having a weak immune system (from an inherited condition, HIV infection, or certain drugs) increases the risk of developing non-Hodgkin's lymphoma.
• Certain infections: Having certain types of infections increases the risk of developing lymphoma. However, lymphoma is not contagious. You cannot "catch" lymphoma from another person. The following are the main types of infection that can increase the risk of lymphoma:
• Human immunodeficiency virus (HIV): HIV is the virus that causes AIDS. People who have HIV infection are at much greater risk of some types of non-Hodgkin's lymphoma.
• Epstein-Barr virus (EBV): Infection with EBV has been linked to an increased risk of lymphoma. In Africa, EBV infection is linked to Burkitt's lymphoma.
• Helicobacter pylori: H. pylori are bacteria that can cause stomach ulcers. They also increase a person's risk of lymphoma in the stomach lining.
• Human T-cell leukemia/lymphoma virus (HTLV-1): Infection with HTLV-1 increases a person's risk of lymphoma and leukemia.
• Hepatitis C virus: Some studies have found an increased risk of lymphoma in people with hepatitis C virus. More research is needed to understand the role of hepatitis C virus.
• Age: Although non-Hodgkin's lymphoma can occur in young people, the chance of developing this disease goes up with age. Most people with non-Hodgkin's lymphoma are older than 60.
Researchers are studying obesity and other possible risk factors for non-Hodgkin's lymphoma. People who work with herbicides or certain other chemicals may be at increased risk of this disease. Researchers are also looking at a possible link between using hair dyes before 1980 and non-Hodgkin's lymphoma.
Most people who have known risk factors do not get non-Hodgkin's lymphoma. On the other hand, people who do get the disease often have no known risk factors. If you think you may be at risk, you should discuss this concern with your doctor.
Non-Hodgkin's lymphoma can cause many symptoms:
• Swollen, painless lymph nodes in the neck, armpits, or groin
• Unexplained weight loss
• Soaking night sweats
• Coughing, trouble breathing, or chest pain
• Weakness and tiredness that don't go away
• Pain, swelling, or a feeling of fullness in the abdomen
Most often, these symptoms are not due to cancer. Infections or other health problems may also cause these symptoms. Anyone with symptoms that do not go away within 2 weeks should see a doctor so that problems can be diagnosed and treated.
If you have swollen lymph nodes or other symptoms that suggest non-Hodgkin's lymphoma, your doctor will help you find out whether they are from cancer or some other cause. Your doctor may ask about your personal and family medical history.
You may have some of the following exams and tests:
• Physical exam: Your doctor checks for swollen lymph nodes in your neck, underarms, and groin. Your doctor also checks your spleen and liver to see if they are swollen.
• Blood tests: The lab does a complete blood count to check the number of blood cells. The lab also checks for other substances, such as lactate dehydrogenase (LDH). Lymphoma may cause a high level of LDH.
• Chest X-rays: You may have X-rays to check for swollen lymph nodes or other signs of disease in your chest.
• Biopsy: Your doctor removes tissue to look for lymphoma cells. A biopsy is the only sure way to diagnose lymphoma. Your doctor may remove an entire lymph node (excisional biopsy) or only part of a lymph node (incisional biopsy). A pathologist checks the tissue for lymphoma cells with a microscope.
The doctor does not remove the tissue sample with a needle (needle biopsy). A needle cannot remove a large enough sample for the pathologist to diagnose lymphoma.
You may want to ask the doctor these questions before having a biopsy:
• How will the biopsy be done?
• Where will I have my biopsy?
• How long will it take?
• Will I be awake?
• Will the biopsy hurt?
• Are there any risks? What are the chances of infection or bleeding after the biopsy?
• How long will it take me to recover?
• How soon will I know the results? Who will explain them to me?
• If I do have cancer, who will talk to me about the next steps? When?
Types of lymphoma
When lymphoma is found, the pathologist will report the type. The most common types are diffuse large B-cell lymphoma and follicular lymphoma.
Lymphomas may be grouped by how quickly they are likely to grow:
• Indolent (also called low-grade) lymphomas grow slowly. They tend to cause few symptoms.
• Aggressive (also called intermediate-grade and high-grade) lymphomas grow and spread more quickly. They tend to cause severe symptoms. Over time, many indolent lymphomas become aggressive lymphomas.
Your doctor needs to know the extent (stage) of non-Hodgkin's lymphoma to plan the best treatment. Staging may involve some of these tests:
• Bone marrow biopsy: The doctor uses a thick needle to remove a small sample of bone and bone marrow from your hipbone or another large bone. Local anesthesia can help control pain. A pathologist then looks for lymphoma cells in the sample.
• CT scan: An X-ray machine linked to a computer takes a series of detailed pictures of your chest, abdomen, or pelvis. You may receive an injection of contrast material. Also, you may be asked to drink another type of contrast material. The contrast material makes it easier for the doctor to see swollen lymph nodes and other abnormal areas on the X-ray.
• MRI: A powerful magnet linked to a computer is used to make detailed pictures of your spinal cord, bone marrow, or brain. Your doctor can view these pictures on a monitor and can print them on film.
• Ultrasound: An ultrasound device sends out sound waves that people cannot hear. The small hand-held device is held against your body. The waves bounce off nearby tissues, and a computer uses the echoes to create a picture. Tumors may produce echoes that are different from the echoes made by healthy tissues. The picture can show possible tumors.
• Lumbar puncture: The doctor uses a long, thin needle to remove fluid from the spinal column. Local anesthesia can help control pain. You must lie flat for a few hours afterward so that you will not get a headache. The lab checks the fluid for lymphoma cells or other problems.
• PET scan: You receive an injection of a small amount of radioactive sugar. A machine makes computerized pictures of the sugar being used by cells in the body. Cancer cells sometimes show up in the pictures as areas of high activity.
The stage is based on where lymphoma cells are found (in the lymph nodes or in other organs or tissues). The stage also depends on how many areas are affected. The stages of non-Hodgkin's lymphoma are as follows:
• Stage I: The lymphoma cells are in a single lymph node group (such as in the neck or underarm). Or, if the abnormal cells are not in the lymph nodes, they are in only one part of a tissue or organ (such as the lung, but not the liver or bone marrow).
• Stage II: The lymphoma cells are in at least two lymph node groups on the same side of (either above or below) the diaphragm. Or, the lymphoma cells are in an organ and the lymph nodes near that organ (on the same side of the diaphragm). There may be lymphoma cells in other lymph node groups on the same side of the diaphragm.
• Stage III: The lymphoma is in groups of lymph nodes above and below the diaphragm. It also may be found in an organ or tissue near these lymph node groups.
• Stage IV: The lymphoma is throughout at least one organ or tissue (in addition to the lymph nodes). Or, it is in the liver, blood, or bone marrow.
For treatment options, go to the article on non-Hodgkin's lymphoma treatment.