Lymphoma is a cancer that affects a part of the immune system called the lymphatic system. Like any cancer, the earlier lymphoma is diagnosed, the easier it is to treat. Anti-HIV drugs significantly reduce the chance of people with HIV developing lymphoma. For people with HIV who have been diagnosed with lymphoma, anti-HIV drugs can help strengthen the immune system and make the cancer easier to treat.
What is lymphoma?
Lymphoma is an umbrella term used to describe different cancers that affect the lymphatic system:
- One type is called Hodgkin’s disease.
- The other types are called non-Hodgkin’s lymphoma.
It is possible for a person with HIV to develop either of these. However, Hodgkin’s disease is rare in people with HIV whereas non-Hodgkin’s lymphoma is considered an AIDS-defining illness—people with HIV are at much higher risk of non-Hodgkin’s lymphoma than the general population.
Lymphoma starts in a type of white blood cell called the B cells. B cells are part of the lymphatic system. An extensive network of vessels that branch out into all parts of the body, the lymphatic system helps fight off infections and diseases. These vessels carry lymph, a clear fluid that contains the B cells. Throughout the lymphatic system, small clusters of tissue, or lymph nodes, trap and filter germs. Larger groups of lymph nodes are found in the neck, armpits and groin. (These are the “swollen glands” you or your doctor may notice when you are ill.)
In addition to lymph nodes, other types of lymphatic tissue throughout your body include the tonsils, spleen, bone marrow and thymus. Because the lymphatic system is so extensive, lymphoma can develop in, and spread to, almost any part of the body, including the spinal cord and brain.
Who is at risk for non-Hodgkin’s lymphoma?
People who have a suppressed immune system—for example, as a result of certain medications, HIV or an organ transplant—are more susceptible to non-Hodgkin’s lymphoma.
For people with HIV who are not taking anti-HIV drugs, the risk of developing non-Hodgkin’s lymphoma increases as the immune system weakens. Research shows that people on anti-HIV drugs are at significantly lower risk of the disease, regardless of their CD4 count.
People with hepatitis C or Epstein-Barr virus and people who have been exposed to certain chemicals (such as chlorinated solvents, formaldehyde and chemicals found in pesticides and herbicides) may also be at higher risk of developing non-Hodgkin’s lymphoma.
The most common symptom of lymphoma is swelling of the lymph nodes in the neck, armpits or groin. This swelling is usually painless. If you notice persistently swollen lymph glands, tell your doctor.
Other symptoms that often accompany swollen lymph nodes include:
- night sweats
- weight loss
Both swollen lymph nodes and the secondary symptoms are common to many illnesses that can affect HIV-positive people.
If lymphoma develops in other parts of the body, it can cause symptoms related to those parts of the body. For example:
- Lymphoma in the gastrointestinal tract may cause abdominal pain or lead to an enlarged liver.
- Lymphoma in the mouth may cause pain and swelling in the mouth.
- Lymphoma in the brain can cause a headache, seizures or difficulty concentrating.
Lymphoma is diagnosed using a procedure called a biopsy. To do a biopsy, a doctor removes a small piece of tissue from the area of concern. That biopsied tissue is later examined under a microscope to determine if lymphoma is present, what types of cells are involved, and how quickly the cancer cells are growing. Based on the speed at which the cells are growing, the lymphoma is classified as
- low grade (spreading slowly);
- intermediate grade (spreading more quickly); or
- high grade (spreading aggressively).
If a biopsy shows lymphoma, your doctor will likely recommend additional tests—such as an X-ray, CT scan, MRI or PET scan—to find out whether the cancer has spread and how far it may have spread. This process, called staging, will help determine the most suitable treatment.
In some cases, an operation called a laparotomy may be done, to allow your doctor to view internal organs and do more biopsies. A bone marrow biopsy and spinal tap may also be required to judge the extent of the lymphoma.
There are many types of lymphoma but they can generally be grouped as follows:
- systemic or peripheral lymphoma—cancers that start in lymph nodes or other lymphatic organs. These may be confined to a small area or spread to other parts of the body.
- primary central nervous system (CNS) lymphoma—lymphoma that first appears in the central nervous system (the brain or spinal cord). It is usually confined to the central nervous system.
Anti-HIV drugs can make non-Hodgkin’s lymphoma easier to treat. Since people with HIV started taking more effective anti-HIV drugs in the 1990s, those diagnosed with non-Hodgkin’s lymphoma have been living longer. Anti-HIV drugs help strengthen the immune system and allow people to handle stronger treatment for the lymphoma.
The cancer treatment your doctor recommends will depend on the type of lymphoma you have, how far it has spread, how quickly it is growing, and your overall health—especially the health of your immune system. Your doctor will recommend one of the following:
A wait-and-see approach
If the lymphoma is growing slowly and has been diagnosed at a very early stage, your doctor may suggest a wait-and-see approach. Treatment may not be necessary. Your doctor will continue to monitor your cancer closely.
If your cancer is spreading more quickly, your doctor may recommend anti-cancer drugs (chemotherapy) or radiation therapy.
Non-Hodgkin’s lymphoma is usually treated with drugs that kill cancer cells, also known as chemotherapy or chemo. The drugs may be taken as pills or injected into a vein (intravenous), into a muscle (intramuscular) or into the fluid that surrounds the spinal cord and brain. Side effects from chemotherapy can include nausea, vomiting, fatigue, diarrhea, sores in the mouth and hair loss. Your doctor may prescribe additional drugs to reduce the side effects.
Radiation therapy may be used instead of, or in addition to, chemotherapy. This treatment uses radiation to help shrink tumours and destroy cancer cells.
- External radiation therapy uses a machine outside the body to direct high-energy x-rays at a specific area of the body. The number of radiation treatments required varies from person to person, depending on the person’s overall health and immune status, the location of the lymphoma, and how well the treatments are tolerated.
- Internal radiation therapy involves placing radioactive material—in the form of seeds, needles or wires—inside the body, in or near the cancer.
Unfortunately, both chemotherapy and radiation treatment weaken the immune system, and can put a person at risk of developing opportunistic infections. Opportunistic infections are potentially life-threatening infections that occur if your immune system is very weakened and your body becomes vulnerable to infections that would not affect you if you were healthy.
Treatment may force the signs and symptoms of the cancer to disappear for weeks, months or even years (the disease is then said to be “in remission”), but the lymphoma can return. However, anti-HIV drugs have dramatically improved the survival rates of HIV-positive individuals who develop non-Hodgkin’s lymphoma and have reduced the number of new cases.
Polesel J, Clifford GM, Rickenbach M et al. Non-Hodgkin’s lymphoma incidence in the Swiss HIV Cohort Study before and after highly active antiretroviral therapy. AIDS. 2008 Jan 11;22(2), 301-6.
Author(s): Koenig D, Maclean D, Sojé P