Unlike cancers related to an organ or a specific part of the body — such as lung cancer or breast cancer — lymphoma can develop at any point within the lymphatic system, and involve one of numerous types of cancers under the larger definitions of Hodgkin’s and non-Hodgkin’s lymphomas. To understand how this cancer can develop, let’s first take a look at the lymph system, how it works, and what happens when it can’t.
What is the lymph system?
Your lymphatic system is an important part of your immune system, and is represented by an extensive network of vessels passing through almost all of the body’s tissues, shuttling a clear liquid called lymph throughout the body.
On this network are around 500 to 700 “lymph nodes” that essentially act as manufacturing stations for lymph — a fluid that contains white blood cells used to defend the body against invaders like viruses and bacteria. One of the main types of these cells is called a lymphocyte, which include T cells and B cells, two of the strongest fighters in your immune system’s army of cells.
Lymph nodes also serve as filtering mechanisms; the lymph system regularly drains excess fluid from body tissues and then routes it though the lymph nodes for assessment by immune system cells.
“Think of it as a whole branching network that runs through your body and works to keep everything well regulated, and as part of that effort, to identify invaders,” says Catherine Diefenbach, M.D., clinical director of lymphoma at NYU Langone Perlmutter Cancer Center, New York.
Lymph nodes are small, bean-shaped structures that are grouped into clusters, particularly in the neck, armpits, groin, chest, and abdomen. Also considered part of the lymph system are bone marrow, the spleen, tonsils, and the thymus.
How does the lymph system work, and how does it fail?
When the lymph system shuttles fluid out of the tissues for examination and finds bacteria or viruses, it traps them and enlists immune cells to attack. This often creates an inflammatory response, causing the nodes in that area to swell, and if it’s in a part of the body where it can be felt externally, you might feel pain or tenderness there, Dr. Diefenbach says. The effect of “swollen glands” is actually enlarged lymph nodes.
You may also experience more aggressive symptoms like night sweats, fever, weight loss, adds Jack F. Jacoub, M.D., medical oncologist and medical director of MemorialCare Cancer Institute at Orange Coast Memorial Medical Center, Fountain Valley, California.
When the system gets out of balance in some way, the process of keeping your body fluids in balance can get out of whack. That can lead to fluid building up in your tissues instead of being shuttled out by the lymph vessels. When that happens, you will likely have swelling — called lymphedema — that can cause issues like infections and blockages. Because your immune system won’t be operating efficiently, it can also leave you more susceptible to illness.
Cancer of the lymph system can arise either because of cells in the system that have turned malignant, or because a lowered immune system allowed cancer cells to go unchecked. In both cases, those cancer cells can spread throughout the body along the lymph system and then grow in lymph node clusters.
If you’re experiencing swelling that doesn’t go away, or having some of the more aggressive symptoms like fever, that should prompt a check with your doctor for possible lymphoma or other conditions that might be affecting the lymph system, advises Dr. Jacoub.
How is lymphoma diagnosed and treated?
Because the lymph system runs throughout the entire body, lymphoma is detected through whole-body imaging like a PET scan or a CAT scan, Dr. Jacoub says. It may also be diagnosed through a bone marrow biopsy. He adds that staging is still evolving, but in general, stage 1 involves a cancer that is in one lymph node region, such as contained in the neck or the groin. Stage 2 is in two or more lymph node regions and may involve one organ as well. Stages 3 and 4 represent a spread beyond the lymph node areas to organs like the liver or lungs.
Both Hodgkin's and non-Hodgkin's lymphoma involve the lymphocytes, but the former has the presence of a certain type of B cell — called a Reed-Sternberg type — that has become malignant. If you don’t have this abnormal cell, you have non-Hodgkin lymphoma.
Unlike some forms of cancer that benefit from tumor removal by surgery, it’s rare for lymphoma to be addressed that way, Dr. Jacoub notes. That’s because it’s considered a “total body illness” due to the way the lymphatic system operates. There are more than 30 types of non-Hodgkin's lymphoma, so specific treatment will be based on what type is present. But in general, says Dr. Jacoub, chemotherapy and targeted radiation are considered the first-line treatments for most lymphomas.