Non-Hodgkin's lymphomas are a type of cancer of the lymphatic system. There are two main types of lymphoma: one is called Hodgkin's disease and the other is called non-Hodgkin's lymphoma. There are about 20 different types of non-Hodgkin's lymphoma. There is only one way to tell the difference between Hodgkin's and non-Hodgkin's lymphomas, and this difference can be seen when the cells are looked at under the microscope. Often the cells need to be stained to show their structures. Usually the cells will also be tested for the presence of particular proteins.

In most cases of Hodgkin's disease, a particular cell known as the Reed-Sternberg cell is found in the biopsies. This cell is not usually found in other lymphomas, so these are called non-Hodgkin's lymphoma. This may not seem a very big difference, but it is important because the treatment for Hodgkin's and non-Hodgkin's lymphomas can be very different.

As medical science has developed over the years, it has been realized that there are over 20 different types of non-Hodgkin's lymphoma, each with its own characteristics and behavior. Non-Hodgkin's lymphomas, like other cancers, are diseases of the body's cells. Cells in different parts of the body may work in different ways but they all repair and reproduce themselves in the same way. Normally, this division of cells takes place in an orderly and controlled manner but if, for some reason, this process gets out of control the cells will continue to divide, so there may be too many immature white blood cells in the blood or bone marrow, and a lump or tumor may develop in one or more groups of lymph nodes.

Lymphocytes move around the body as part of their role in defending against infection, and so lymphoma cells can sometimes travel through the lymphatic system to lymph nodes in other parts of the body. The lymphoma cells can also go into the bloodstream, which may carry them to other organs. When the cells reach a new area they may go on dividing and form a new tumor

There are over 20 different types of non-Hodgkin's lymphoma. Each type has:

A particular appearance when looked at under the microscope Specific types of proteins on the surface of the cells A particular rate of growth Its own specific treatments.

Different types of NHL affect the body in different ways. The main types are listed below:

• B-cell lymphomas
• Precursor B lymphoblastic
• Small lymphocytic
• B-cell prolymphocytic
• Lymphoplasmacytic
• Splenic marginal zone
• Extranodal marginal zone - MALT
• Nodal marginal zone
• Follicular
• Mantle cell
• Diffuse large B-cell
• Primary mediastinal large B-cell
• Primary effusion
• Burkett’s
• T-cell lymphomas
• Precursor (peripheral) T-cell lymphoblastic
• Adult T-cell
• Extranodal Natural Killer/T-cell, nasal type
• Enteropathy type T-cell
• Hepatosplenic T-cell
• Subcutaneous panniculitis like T-cell
• Skin (cutaneous) lymphomas- including Mycosis fungoides/ Sézary syndrome
• Anaplastic large cell
• Peripheral T-cell, not otherwise specified
• Angioimmunoblastic T-cell
• AIDS related
• Central nervous system lymphoma

Most people have B-cell lymphomas, with T-cell lymphomas occurring more often in adolescents and young adults. Knowing the grade and stage of a lymphoma helps the doctors to know how the lymphoma is likely to develop, how it may affect you and which treatment is most appropriate.

Grading refers to the appearance of the lymphoma cells under the microscope. The grade gives an idea of how quickly the lymphoma may grow and develop. For practical reasons non-Hodgkin's lymphomas are generally divided into two main categories:

Low-grade (or slow-growing): these have a very slow growth rate and may need little or no treatment for months or possibly years. When they do need treatment they are likely to shrink down, or even disappear completely, but are likely to come back again at some time in the future.

High-grade (or faster-growing): these types grow more quickly and are more likely to spread to other lymph nodes or other organs in the body. They are more likely to cause symptoms and usually need immediate treatment. However, they are more likely to be completely cured than low grade lymphomas. The usual treatment is intensive chemotherapy.

The stage of a lymphoma is a term used to describe where it is in the body, how many lymph glands are affected and whether it has spread to other lymph glands or other organs. A commonly used staging system is described below:

Stage 1: One group of lymph nodes is affected.

Stage 2: Two or more groups of nodes are affected but the lymphoma is only on one side of the diaphragm. The diaphragm is the sheet of muscle under the lungs that plays a large part in our breathing. The part of the body above the diaphragm is considered the upper half, and below the diaphragm is considered the lower half of the body.

Stage 3: The lymphoma is in lymph nodes on both sides of the diaphragm.

Stage 4: The lymphoma has spread beyond the lymph nodes, for example to other organs such as the bone marrow, liver or lungs.

As well as giving each stage a number, doctors also use a letter code - either A or B - to show whether or not you have specific symptoms. Your doctor will ask you whether you have lost weight or have fevers or night sweats. If you do not have any of these symptoms, your lymphoma will be classified as A. If you have these symptoms, it is B.

Occasionally, lymphomas can arise at unusual sites outside the lymph nodes, for example in the stomach. This is called extranodal lymphoma and the stage will include the letter E (for extranodal). Once your doctor knows the type of lymphoma and the stage and grade, he or she can plan the most effective treatment for you.

Like most types of cancer the cause of most non-Hodgkin's lymphomas is unknown. It is known that lymphomas are more likely to develop in people who have taken drugs to prevent rejection following an organ transplant or whose immunity has been reduced, for example in people with HIV or AIDS.

However, despite the increased risk, NHL is still uncommon in these people. Certain viruses such as the Epstein Barr virus, which causes glandular fever, can contribute to the development of lymphomas, but, like other cancers, lymphomas are not infectious and cannot be passed on to other people. One rare type of lymphoma, which usually affects the stomach - MALT lymphoma - is known to be caused by a type of bacterial infection known as helicobacter pylori.

It is thought that lymphomas are not caused by genetic changes that can be passed down through families, so they are not inherited.

Symptoms
Often, the first sign of a non-Hodgkin's lymphoma is a painless swelling of a lymph node in the neck, armpit or groin.
Other symptoms may include any of the following:

• Night sweats or unexplained high temperatures (fever).
• Loss of appetite, unexplained weight loss and excessive tiredness.
• Children may develop a cough or breathlessness. They may also complain of abdominal pain or you may notice a lump in your child's abdomen.
• Persistent itching of the skin all over the body.

If you or your child have any of the above symptoms you must have them checked by your doctor. However, they are common to many conditions other than non-Hodgkin's lymphoma and most people with these symptoms will not have a lymphoma.

A definite diagnosis is made by removing an enlarged lymph node or part of it, and examining the cells under a microscope. This is known as a biopsy. It is a very small procedure and may be done under local anesthetic and sedation, or a general anesthetic. Biopsies may also be taken from other body tissues.

If the biopsy shows that lymphoma cells are present, your doctor will want you to have some further tests to find out the exact stage of the disease. Staging is a way of describing the extent and spread of the cancer in your body. It is very important because the type of treatment you receive depends on the stage of the disease.

The tests that may be done to find out the stage of your lymphoma may include any of the following:

Blood tests
Samples of your blood will be taken regularly throughout your treatment to check your general health, the levels of red cells, white cells and platelets in your blood, and your liver and kidney function.

Chest x-ray
This is taken to check for any sign that the lymphoma has spread to the lymph nodes in the chest or to the lungs.

Bone marrow sample
For this test a sample of bone marrow is taken, usually from the back of the hip bones. The sample is then examined to see if it contains any lymphoma cells. The test does not take very long and can be done on the ward or in the outpatient department. If you are very anxious about the test a mild sedative may be helpful, so ask your doctor about this beforehand.

Ultrasound scan
Ultrasound scans use sound waves to make up a picture of the inside of the body to check for any abnormalities. It will be done in the hospital scanning department.

CT scan (Computerized tomography)
This is a series of x-rays, which builds up a three-dimensional picture of the inside of the body. The scan is painless. It takes longer than an x-ray (from 10 to 30 minutes) and can be used to find how many lymph nodes are affected by the lymphoma, or whether lymph glands in other areas of the body are affected.

The following tests are less commonly done but may be considered necessary in some cases:

Lumbar puncture
MRI scan (Magnetic resonance imaging)
PET scan (Positron Emission Tomography)

Conventional Treatment
The conventional treatment of non-Hodgkin's lymphomas has greatly improved over the past few years, even when they have spread to different areas of the body. Many people can now either be cured or stay in remission for many years. Complete remission is where there is no sign of the lymphoma. Partial remission is where the lymphoma shrinks down so that the person is well, does not have symptoms and does not need further treatment at that time.

For many people in the early stages of some types of low grade lymphoma no treatment may be needed at first. Where treatment is needed the main types are radiotherapy and chemotherapy. You may need either of these treatments, or a combination of both.

Children with non-Hodgkin's lymphoma nearly always have high-grade tumors and the main form of treatment is with intensive chemotherapy. Radiotherapy may sometimes be necessary as well. CancerBACUP has a booklet on children's cancers which has more information about non-Hodgkin's lymphoma in children and its treatment.

Steroids are drugs which are often given with chemotherapy to help treat lymphomas. They also help you to feel better and can reduce feelings of sickness.

Monoclonal antibodies are drugs that can `recognize' and find specific cells in the body. These drugs can be designed to find a particular type of cancer cell, attach itself to them and destroy them. They can be used alone, or a radioactive molecule can be attached to a monoclonal antibody, which then delivers radiation directly to the cancer cells.

Excerpted from the CancerBACUP booklet series.