Metastases to Lymph Nodes
When cancer spreads beyond its original location, lymph nodes are often the first place it travels to. Understanding how cancer moves through the lymphatic system and what it means for treatment can help patients navigate this challenging diagnosis.
Table of contents
- What Are Lymph Nodes?
- What Is Lymph Node Metastasis?
- How Cancer Spreads to Lymph Nodes
- Signs and Symptoms
- Diagnosis and Testing
- Clinical Significance
- Treatment Approaches
What Are Lymph Nodes
Lymph nodes are small, bean-shaped organs that play an essential role in your body’s defense system. Everyone has hundreds of lymph nodes spread throughout their body, working together as part of the immune system.[1]
These tiny structures act as filters for infections, cancer cells, and disease. They are located in various parts of the body, including the neck, armpit, chest, abdomen, and groin. Some lymph nodes are positioned deep inside your body, while others are closer to the surface.[1]
The lymph nodes work through a network of vessels called the lymphatic system, which transports fluid throughout your body. This fluid, known as lymph, contains immune cells that fight off and destroy harmful germs as they are carried through the body. All of your lymph nodes are connected, and the lymph fluid flows from various parts of your body toward your chest.[1]
In their normal role, lymph nodes serve as training centers for immune cells. Inside these nodes, immune cells learn how to fight infections and cancer. Once fully trained, these cells leave the lymph nodes to monitor the body for threats.[3]
What Is Lymph Node Metastasis?
Lymph node metastasis occurs when cancer cells spread from their original location to the lymph nodes. This is different from lymphoma, which is cancer that starts in the lymph nodes themselves. When doctors talk about metastases to lymph nodes, they mean cancer that began elsewhere in the body and then traveled to the nodes.[7]
Cancer cells in metastatic lymph nodes look the same under a microscope as the cells from the original tumor. For example, if pancreatic cancer spreads to lymph nodes, the cancer cells in the nodes will still look like pancreatic cancer cells and are treated accordingly.[1]
Lymph node metastasis can happen in several ways. Cancer may be found in lymph nodes near the primary cancer site, which is called regional metastasis. During cancer surgery, surgeons routinely remove nearby lymph nodes to test them for cancer cells. Finding cancer cells in the lymphatic system means there is a much higher chance the cancer could come back.[1]
Sometimes cancer cells travel quite far from the original site and settle in distant lymph nodes. When this happens, it is called secondary or metastatic cancer.[1] The presence of cancer in lymph nodes is considered a form of regional metastasis, as opposed to distant metastases to organs like the liver, bones, or brain.[7]
How Cancer Spreads to Lymph Nodes
Cancer spreads to lymph nodes through the lymphatic vessels that carry fluid throughout the body. When cancer cells break off from the original tumor, they can enter these vessels and travel through the lymph to reach nearby or distant lymph nodes.[2]
Generally, cancer forms metastases first in the lymph nodes that are closest to the primary tumor. This happens because lymph fluid from the cancerous organ or tissue flows first to these nearby nodes. The cancer cells reach the lymph nodes through this pathway, where they remain and begin to multiply.[7]
The likelihood of cancer spreading to lymph nodes depends on several factors, including the density of lymphatic vessels in the area of the original tumor. Some types of cancer, such as breast cancer, pancreatic cancer, head and neck cancer, and melanoma, commonly spread to lymph nodes as their first site of metastasis.[7]
Recent research has revealed that lymph nodes are not just passive sites where cancer cells get trapped. Studies in mice suggest that cancer cells in lymph nodes can actually manipulate the immune system. Instead of being attacked by immune cells, the cancer cells convince these defenders to help protect the tumor rather than destroy it. This gives the cancer a way to spread more easily to other parts of the body.[3]
Once cancer cells grow in the lymph nodes, they can later detach from these metastases, enter the bloodstream, and lead to distant metastases in other organs through what is called hematogenous spread (spreading through the blood).[7]
Signs and Symptoms
Lymph node metastasis symptoms can vary widely from person to person. The most common sign is that one or more lymph nodes become hard or swollen. However, many people might not feel anything at all, especially if the affected lymph nodes are located deep inside the abdomen or around internal organs.[1]
Enlarged lymph nodes caused by cancer are usually painless. This is different from lymphadenitis (inflammation of lymph nodes from infection, such as a viral illness), where the nodes are both swollen and tender when touched.[7]
If the affected lymph node presses on nearby organs or structures, various symptoms may develop. When lymph nodes press on blood vessels, it can interfere with blood flow and potentially lead to blood clotting. This may cause redness, pain, swelling, trouble breathing, or chest pain.[1]
In severe cases, cancer cells can block the normal flow of lymph fluid throughout the body. When this blockage occurs in the arms or legs, it leads to a condition called lymphedema, which causes swelling, reduced mobility, pain, and possible infection.[1]
Metastasis to lymph nodes doesn’t always cause immediate symptoms. Cancer cells can grow and spread gradually over many months or years. In some cases, it is possible to have advanced cancer and not know it initially.[2]
Diagnosis and Testing
When lymph nodes are close to the skin surface, such as in the neck or armpit, enlarged nodes can be identified by your doctor pressing on these areas to feel for lumps. This examination method is called palpation.[7]
Several imaging tests can help detect enlarged lymph nodes that are not visible or easily felt from the outside. Ultrasound (also called sonography) uses sound waves to create images and is especially useful for evaluating lymph nodes located close to the skin surface, such as in the armpit or groin.[7]
Other imaging methods include CT scans (computed tomography), MRI scans (magnetic resonance imaging), and PET scans (positron emission tomography). These tests can detect enlarged lymph nodes in deeper locations like the chest or abdomen.[2]
If imaging reveals enlarged or suspicious lymph nodes, a biopsy is usually performed to confirm whether cancer is present. During a biopsy, a small sample of tissue is removed from the lymph node and examined under a microscope.[2]
For certain cancers, particularly breast cancer and skin cancer, a sentinel node biopsy is commonly performed during surgery. In this procedure, doctors identify and remove the first few lymph nodes that drain from the tumor area (the sentinel nodes) to check for cancer. This approach helps determine if cancer has spread while minimizing the number of lymph nodes that need to be removed.[18]
Your healthcare provider may also use blood tests, bone scans, tumor marker-based tests, ultrasound, or X-rays as part of the diagnostic process.[2]
Clinical Significance
The presence or absence of cancer in lymph nodes is one of the most important factors doctors consider when evaluating cancer patients. Lymph node metastasis has major implications for disease staging, treatment decisions, and predicting outcomes.[6]
When cancer spreads to lymph nodes, it usually indicates that the disease is at stage 2 or 3. Many cancers at this stage are still treatable and may even be curable. Cancer that has spread widely throughout the body to distant organs is considered metastatic or stage 4 cancer.[18]
Lymph node metastasis is usually classified using the TNM staging system, where T stands for tumor, N stands for nodes (lymph nodes), and M stands for metastasis. N0 means there are no signs of lymph node involvement, while higher numbers indicate increasing levels of spread to lymph nodes. However, staging systems can vary depending on the type of cancer.[7]
Finding cancer in nearby lymph nodes generally means the disease is more advanced than if the lymph nodes were clear. If someone is found to have cancer in their lymph nodes, it is usually a concerning sign that the cancer has spread or may soon spread to other parts of the body.[3]
Studies have shown that patients with cancer detected in lymph nodes during examination (but not yet visible or causing symptoms) tend to have better survival rates than patients whose lymph nodes are visibly enlarged with cancer. The 5- and 10-year survival is approximately 25% higher for patients with small amounts of cancer in lymph nodes detected during surgery compared to those with obviously enlarged, cancer-filled lymph nodes.[10]
Lymph nodes serve as important hubs where cancer cells can arrest and grow, where immune responses are modified, and from which cancer can spread further to distant organs. Understanding the role of lymph nodes in cancer progression helps doctors provide patients with accurate disease assessment and develop effective treatment strategies.[6]
Treatment Approaches
When cancer has spread to lymph nodes, several treatment options are available. The specific approach depends on where the cancer started in the body, how far it has spread, and other individual factors.[2]
Surgery is currently the only effective treatment for removing cancer that has spread to lymph nodes. When performed to remove visibly enlarged, cancer-filled lymph nodes, the procedure is called therapeutic lymphadenectomy. Surgical removal of involved lymph nodes offers the best chance for local control of the disease and potential cure.[10]
In addition to surgery, cancer that has spread to lymph nodes may be treated with chemotherapy, radiation therapy, or other anti-cancer medicines. These can include targeted therapies such as antibodies, CAR-T cell treatments, or small molecule drugs. Often, a combination of these treatments is used.[18]
Healthcare providers treat metastasis based on where the cancer originally started. For example, if breast cancer spreads to lymph nodes, doctors will still treat it using breast cancer protocols, not as a separate disease.[2]
One important consideration with lymph node surgery is the risk of lymphedema. When lymph nodes are removed from the armpits or groin, 30% to 50% of patients will develop swelling in their arms or legs. This occurs because removing nodes disrupts the normal flow of lymph fluid, causing it to build up in the limbs. Lymphedema can lead to pain, reduced mobility, and increased risk of infection.[18]
Because of the risk of lymphedema and other complications, researchers are studying whether radiation therapy might be a better alternative to surgery in some cases. Several studies are currently in progress to compare these approaches.[18]
While doctors cannot cure most metastatic cancers, treatment can help manage symptoms and in many cases extend survival. Some patients with metastatic disease, including those with lymph node involvement, can live for many years with appropriate treatment.[2]
If you notice a swollen lymph node that does not improve after two weeks, you should consider making an appointment with your doctor to have it evaluated, as lymph nodes can become swollen from infection as well as cancer.[18]
