What to Know About Lymph Nodes and Cancer

When cancer cells begin in the lymph nodes, the cancer is known as lymphoma. Cancer cells can also start in other areas of the body and spread to the lymph nodes in a process known as metastasis. They can then spread through the lymphatic system to other areas of the body, making the cancer more serious and challenging to treat. One of the first symptoms of cancer in the lymph nodes is usually lymphadenopathy, which refers to swelling of the lymph nodes. 

Function of Lymph Nodes

The lymph nodes are part of the lymphatic system, an important element in our body’s immune system. The lymphatic system collects fluid that is outside of the bloodstream throughout the body. This clear fluid, known as lymph, can contain waste materials, bacteria, and viruses. It also carries oxygen and other nutrients to cells throughout the body. Lymph can help fight infections, because it contains white blood cells known as lymphocytes. The lymph vessels then carry lymph fluid to the chest, where it can be collected into a large blood vessel.  

As the lymph vessels move the fluid around the body, lymph nodes work as filters for harmful substances like viruses or bacteria. The lymph nodes contain immune cells that attack the harmful material, preventing it from spreading around the body. There are lymph nodes spread throughout the entire body, including under the arms, in the neck, and in the groin. 

When the lymph nodes are compromised, such as from cancer or an infection, they can grow in size. The swelling is called lymphadenopathy and is a result of the nodes trying to filter out harmful substances. Possible causes of lymphadenopathy include infections, injury to the lymph nodes, medications, immune system disorders, and cancer. The cancers most commonly responsible for enlarged lymph nodes are lymphoma and leukemia. Swollen lymph nodes are relatively common, however, and rarely mean cancer. 

Types of Lymph Node Cancer

There are two possibilities for developing cancer in the lymph nodes. First, primary lymph node cancers are grouped under the name lymphomas, and they start in the lymph nodes. Secondary lymph node cancers begin in other areas of the body and then spread to the lymph nodes through metastasis.

Lymphoma

Lymphoma, the most common type of blood cancer, originates in the lymphocytes. Once these cells have mutated and become cancerous, they can spread to the lymph nodes, spleen, bone marrow, and other organs. 

There are two broad classifications for lymphoma. 

• Hodgkin lymphoma is a rare type of cancer that originates in the Reed-Sternberg cells (large, abnormal lymphocytes that may contain more than one nucleus). It can begin anywhere in the body, but is most commonly found in the upper part of the body, at the chest, neck, or underarms. It usually spreads through the lymphatic system and causes lymphadenopathy in areas that are involved. 
• Non-Hodgkin lymphoma refers to any lymphoma that does not involve the Reed-Sternberg cells. There are 90 different types, and more than 80,000 people in the United States are diagnosed with one of these lymphomas every year. The most common sites for non-Hodgkin lymphoma to develop are the lymph nodes, spleen, bone marrow, thymus, digestive tract, and tonsils and adenoids. It often causes generalized lymphadenopathy throughout the body.

Metastasis

When cancer cells break away from their primary site tumor, they can travel through the blood vessels or lymphatic system. When they travel through the lymphatic system, they will come in contact with the nearest lymph node. Fortunately, these cancer cells are usually destroyed before they’re able to start multiplying. Sometimes they can attach to the lymph node and start replicating there. This most often happens in the lymph node closest to the primary tumor, which has been working overtime trying to filter out the cancer cells from the tumor. 

It is also possible for cancer cells to travel through the blood vessels to areas of the body that are far away from the primary tumor. Once this happens, cancer may be found in lymph nodes distant from the original tumor because a new tumor has formed in another organ. The most common symptoms of metastatic cancer are weakness, unintentional weight loss, pain, and shortness of breath. 

Symptoms

Symptoms of lymph node cancer can resemble a cold or common virus, and usually mean that your body is fighting off an infection. It’s possible to experience a fever, chills, sweating, and lack of energy. The most common symptom of cancer in the lymph nodes is lymphadenopathy.

Normal lymph nodes are too small to feel with your fingers. If you notice a feeling of small, hard lumps under the skin in your underarms, neck, or groin, it could mean that your lymph nodes are swollen. On their own, none of these symptoms automatically mean cancer. The more common cause are viral or bacterial infections such as strep throat or mononucleosis. 

Diagnosis

The only way to diagnose cancer in a lymph node is with a biopsy. Your healthcare provider will start by asking questions and performing a physical exam. The type of biopsy your healthcare provider chooses to perform will depend on the characteristics of the lymph node, as well as your other symptoms.

Your healthcare provider may remove an entire lymph node, which is called an excisional biopsy. Removing a portion of the lymph node is called an incisional biopsy. In addition, removing one lymph node is called a biopsy, and removing multiple nodes is called lymph node dissection or sampling. 

Your healthcare provider is also able to perform a needle biopsy, during which cells from the lymph node are removed with a syringe and examined under a microscope. A needle biopsy is less invasive, but it does not always provide a large enough sample to confirm a diagnosis. This is usually chosen when your healthcare provider suspects another cause for your swollen lymph nodes, such as infection. A fine-needle aspiration biopsy uses a very thin needle to remove cells from the lymph node, while a core needle biopsy uses a larger needle. 

Once the sample is obtained, a pathologist examines the sample under a microscope. If there is secondary cancer present in the lymph nodes, the cells will resemble cells from the primary organ. For example, if lung cancer cells traveled to the lymph node, cells from the lymph node will resemble lung cells. 

A pathologist will evaluate the sample with flow cytometry or immunohistochemistry. In these processes, the sample is treated with antibodies that bind to certain proteins. Different types of lymphocytes have different proteins on their surfaces. This can tell the pathologist if the cells are cancerous and which type of cancer is present. 

If your medical team suspects that you have primary cancer that has metastasized, or that you have lymphoma, they may recommend a positron emission tomography (PET) scan to find other areas of the body that may be involved.

Staging

The lymph nodes play a critical role in how cancer is staged. Staging is needed to determine where your cancer is and how advanced it has become. Treatment will depend largely on what stage your cancer has been classified as.

The TNM system is used to stage most types of cancer:

• Tumor: The original (primary) tumor
• Nodes: If the cancer has spread to the lymph nodes
• Metastasis: Whether the cancer has metastasized

Once your medical team has determined where the primary site of cancer is, they will then examine the surrounding lymph nodes to determine how much the cancer has spread. When there is no cancer in the lymph nodes, the N value is 0. Usually, the lower the TNM stage, the easier the cancer should be to treat. Each case is unique, however, and the stage does not necessarily determine the outcome. For example, a study of patients with triple-receptor-negative breast cancer found that once the cancer metastasized, the number of positive lymph nodes did not seem to affect prognosis.  

Treatment

Treatment for lymphoma usually involves some combination of chemotherapy, radiation therapy, and immunotherapy. Patients with non-Hodgkin lymphoma may also require a bone marrow transplant, stem cell transplant, or CAR T-cell therapy. Surgery is usually only used for diagnosis. 

When a lymph node needs to be removed, it is usually done under general anesthesia. The lymph node, along with the surrounding lymphatic tissue and soft tissue, is removed and dissected. One of the most common side effects of lymphadenectomy is lymphedema. This occurs when the lymph fluid no longer drains correctly and backs up at the site of the removed lymph node. Other possible side effects of the surgery include numbness, tingling, pain, and skin sloughing at the site. 

Unfortunately, once a primary tumor has spread to the lymph nodes, it is more likely to recur. For this reason, cancer that has spread to the lymph nodes is usually treated with radiation and chemotherapy as well as surgery. 

A Word From Verywell

If you have noticed enlarged or hard lymph nodes, it’s natural to feel anxious about it. It’s helpful to remember that cancer is usually the least likely explanation. It is important, however, to see a healthcare provider right away to figure out why they are swollen as well as what treatment is needed. An early cancer diagnosis almost always leads to better outcomes than a late one.