Non-Hodgkin’s lymphoma

What is non-Hodgkin’s lymphoma?

Non-Hodgkin’s lymphoma is a disease in which cancerous (or malignant) cells are found in the lymph system. The lymph system is made up of thin tubes that branch like blood vessels into all parts of the body. Lymph vessels carry lymph, a colorless, watery fluid that contains white blood cells called lymphocytes, which are specialized immune system cells. Along the network of vessels are groups of small organs called lymph nodes, which make and store infection-fighting cells such as lymphocytes. Clusters of lymph nodes are found in the underarms, pelvis, neck and abdomen. The spleen, thymus and tonsils are also part of the lymph system.

Based on how the cancer cells look under a microscope, lymphomas (cancers of the lymph system) are divided into two general types: Hodgkin’s disease and non-Hodgkin’s lymphomas. Non-Hodgkin’s lymphoma can occur in both adults and children and is treated differently than Hodgkin’s disease. There are many types of non-Hodgkin’s lymphomas, which are also categorized based on how the cells look microscopically. The two types of non-Hodgkin’s lymphomas are indolent lymphomas, which are slower growing and have fewer symptoms, and aggressive lymphomas, which grow more quickly. Because lymph tissue is found in many parts of the body, non-Hodgkin’s lymphoma can start almost anywhere. The cancer can spread to almost any organ or tissue, including the liver, bone marrow, spleen and nose.

How many people get non-Hodgkin’s lymphoma?

It is estimated that in 2007, 63,190 Americans, including adults and children, will be diagnosed with non-Hodgkin’s lymphoma, and that 18,660 will die from the disease. Non-Hodgkin’s lymphoma is somewhat more common in men than in women, and whites are more often affected than African Americans or Asian Americans. More than 90 percent of non-Hodgkin’s lymphoma cases occur in adults.

What causes non-Hodgkin’s lymphoma?

Although researchers have found that non-Hodgkin's lymphoma is associated with a number of risk factors, most patients with non-Hodgkin’s lymphoma do not have any known risk factors and the causes of their cancers are unknown.

Non-Hodgkin’s lymphoma appears to be related to DNA mutations that are usually acquired after birth, rather than being inherited. Acquired mutations may result from exposure to carcinogens, although these mutations often occur for no apparent reason. Non-Hodgkin’s lymphoma can also develop when DNA spontaneously translocates from one chromosome to a different chromosome. If the translocated DNA was originally located within a gene involved in suppressing tumor development and growth—or moved into such a “tumor suppressive” area of a chromosome—the body’s ability to fight cancers may be negatively affected.

Non-Hodgkin’s lymphoma is also related to certain inherited genetic risk factors. For example, some genetic diseases cause children to be born with an abnormal or deficient immune system. In addition to developing serious infections due to reduced immune defenses, they have an increased risk of developing non-Hodgkin’s lymphoma during childhood or as young adults.

Environmental risk factors (influences in our surroundings such as radiation, chemicals and infections) may also play in role in the development of non-Hodgkin’s lymphoma. Some examples are listed below.

Radiation

Survivors of atomic bombs and nuclear reactor accidents have an increased risk of developing several types of cancer, including leukemia, thyroid cancer, and non-Hodgkin’s lymphoma. Patients treated with radiation therapy for some other cancers have a slight risk of developing non-Hodgkin’s lymphoma later in life, and patients treated with both radiation therapy and chemotherapy are more likely to develop secondary leukemias or non-Hodgkin’s lymphomas.

Chemicals

Some chemotherapy drugs used to treat other cancers can increase the risk of developing leukemia or non-Hodgkin’s lymphoma five to 10 years later. For example, patients who have been treated for Hodgkin’s disease have a 4 percent to 5 percent risk of developing non-Hodgkin’s lymphoma over a 10-year period. In addition, research is underway to determine if exposure to chemicals such as benzene and certain herbicides and insecticides (weed- and insect-killing substances) are associated with an increased risk of developing non-Hodgkin’s lymphoma.

Immune deficiency

Research shows that the chance of developing lymphoma is about 100 times greater for immunocompromised people and may be related to certain viral infections (see below).

Infections

Infection with the human T-cell leukemia/lymphoma virus (HTLV-1) increases a person’s risk of developing certain types of T-cell, non-Hodgkin’s lymphoma. This virus is most common in some parts of Japan and in the Caribbean region. In fact, in some areas of Japan, it is responsible for about half of the non-Hodgkin’s lymphoma cases. In the United States, HTLV-1 infection causes less than 1 percent of lymphomas. In the same family of viruses as HIV, HTLV-1 spreads through sexual intercourse, contaminated blood, and can be passed to children through breast milk.

In areas of Africa where Burkitt’s lymphoma (a type of non-Hodgkin’s lymphoma that most often occurs in young people between the ages of 12 and 30) is common, infection with malaria and the Epstein-Barr virus are important risk factors for this disease.

Scientists have recently found that Helicobacter pylori bacteria, which is known to cause stomach ulcers, can also cause some lymphomas of the stomach. The body’s immune reaction to this infection causes excess growth of certain types of lymphocytes, which increases the risk for certain types of non-Hodgkin’s lymphoma.

What are the symptoms of non-Hodgkin’s lymphoma?

Non-Hodgkin’s lymphoma may cause many different signs and symptoms, depending on the location of the involvement.

Non-Hodgkin's lymphoma that involves easily seen or palpated (felt) lymph nodes close to the surface of the body (e.g., lymph nodes on the sides of the neck, in the groin or underarm areas, above the collar bone) are usually noticed by the patient, a family member or a health care professional.

When the lymphoid tissue inside the abdomen is involved, the abdomen can be swollen—sometimes so much that it may resemble pregnancy in a woman. This may be due to large collections of fluid or cancerous tissue. Sometimes the cancer damages the lining layer of the abdominal cavity and causes large amounts of fluid to build up. When lymphoma causes swelling of lymphoid tissue near the intestines, passage of feces through the compressed area may be blocked. The pressure or blockage can also cause discomfort or abdominal pain.

When lymphoma starts in the thymus, irritation or compression of the nearby trachea (windpipe) can cause coughing, shortness of breath or suffocation. Growth of lymphoma may compress the superior vena cava (SVC), which is the large vein that carries blood from the head and arms back to the heart. This causes swelling of the head and arms known as SVC syndrome, which can also affect the brain and become life threatening. Patients with SVC syndrome need to be treated as soon as possible.

In addition to symptoms and signs resulting from local effects of cancer growth, non-Hodgkin’s lymphoma can produce generalized symptoms such as unexplained weight loss, fever, profuse sweating (enough to soak clothing), particularly at night, or severe itchiness. Oncologists sometimes call these generalized effects B symptoms. The presence of B symptoms is associated with a poor outlook and is related to an increased tumor burden (more cancer cells) in some patients.

How is non-Hodgkin’s lymphoma diagnosed?

The symptoms of non-Hodgkin’s lymphoma are not unique enough for a doctor to know for certain whether cancer is present. Most symptoms can also be caused by noncancerous problems like infections or by other kinds of cancers. A biopsy is the only way to reach an accurate diagnosis. There are several biopsy procedures (e.g., fine needle aspiration biopsy, excisional or incisional biopsy, bone marrow aspiration and biopsy, lumbar puncture/spinal tap) and doctors choose which to use based on the unique aspects of each patient’s situation.

If microscopic examination of the biopsied tissue does not provide a definite answer, other laboratory tests are usually needed, such as immunohistochemistry, flow cytometry, cytogenetics, or molecular genetic studies. In addition, the doctor may conduct imaging studies such as chest X-ray, CT scan, MRI or gallium scan to help diagnose non-Hodgkin’s lymphoma and determine how far it may have spread.

How is non-Hodgkin’s lymphoma staged?

Staging is the process of finding out how far the cancer has spread. It is very important because, to a large extent, treatment and outlook for recovery depend on the stage of the cancer. The staging system most often used to describe the spread of non-Hodgkin’s lymphoma in adults is called the Ann Arbor staging system and is described below.

Is non-Hodgkin’s lymphoma fatal?

Overall, the one-year relative survival rate for non-Hodgkin’s lymphoma is 70 percent, and the five-year survival rate is 51 percent.

These survival rates describe the percentage of patients who live at least one or five years after their cancer is diagnosed and exclude patients dying of other diseases. This means that anyone who died of another cause, such as heart disease, is not counted in these rates.

How is non-Hodgkin’s lymphoma treated?

The main treatments for non-Hodgkin’s lymphoma are chemotherapy and/or radiation therapy, which can be used alone or together depending on the type and location of the lymphoma. New treatment approaches include immunotherapy, bone marrow transplantation, and surgery.

Below are additional resources that may be helpful to you.