What Happens When Cancer Spreads to the Lymph Nodes?

As part of diagnosing cancer, healthcare providers check to see if cancer has spread to your lymph nodes. This information helps them figure out how advanced the cancer is and guides treatment decisions.

But what does it really mean? What happens when cancer spreads to your lymph nodes? Oncologist Shimoli Barot, MD, explains.

What it means if cancer is in your lymph nodes

Cancer cells found in lymph nodes can indicate a primary cancer (like lymphoma), which begins in lymph nodes or vessels. But a cancer that has spread to your lymph nodes is a secondary cancer — one that started elsewhere in your body and is using your lymphatic system to spread.

“Cancer tends to grow and spread by finding the most favorable conditions in the body,” Dr. Barot says. “When we detect cancer cells in the lymph nodes, but the cancer didn’t start there, it means the cancer is beginning to spread to other areas.”

But how did the cancer get there? To understand that, let’s back up.

Your lymphatic system, which is an important part of your immune defense, helps protect against disease and infection. It circulates a fluid called lymph throughout your body, passing through small “filtering stations” called lymph nodes. There, white blood cells work to identify and destroy harmful invaders like bacteria and viruses.

But cancer cells can spread by taking advantage of this system.

Dr. Barot explains that when cancer cells break away from a tumor, they often travel first to nearby lymph nodes. Cancer can also spread through your bloodstream and lymphatic system to distant lymph nodes and organs in your body.

“When we find cancer cells in the lymph nodes, it tells us they were able to evade the immune response,” she continues. “This suggests that the cancer has begun to spread, and the immune system couldn’t fully eliminate those cells.”

How to tell if cancer has spread to the lymph nodes

When the immune cells in your lymph nodes are actively fighting harmful bacteria or abnormal cells, you may notice:

• Swelling, which you can feel if the nodes are closer to the surface, like those in your neck, armpit or groin
• Pain or pressure if deeper lymph nodes are pressing on nearby organs or tissues

On the other hand, if there are just a few cancer cells in your lymph nodes, you may not feel anything. So, your provider may take a closer look at your lymph nodes using diagnostic tools, such as:

• Imaging, like CT, MRI, PET scans and lymphoscintigraphy, which can identify the first node the cancer likely spread to (aka the sentinel lymph node)
• Biopsy, which may involve removing one or more lymph nodes (excision or sentinel lymph node biopsy) or taking a sample of lymph fluid and cells by needle

“Sometimes, lymph nodes feel completely normal, but under the microscope, we discover cancer cells,” Dr. Barot shares.

What are the next steps if cancer has spread to the lymph nodes?

If cancer is found in lymph nodes and appears to be spreading, next steps may include:

• Additional testing to see how far the cancer has spread
• Lymph node removal to eliminate the cancer cells
• Whole-body (systemic) treatment to target cancer cells throughout your body

If cancer cells break away from the original tumor and spread, they can grow in other parts of your body — a process called metastasis. No matter where cancer is found, the goal of treatment is to contain, remove or destroy cancer cells before they have a chance to grow or spread any farther.

“When cancer spreads beyond the nearest lymph nodes, we treat it differently than when if it’s confined to one area,” Dr. Barot clarifies. “For example, breast cancer that spreads to lymph nodes in the chest or abdomen requires a different approach than breast cancer that is still only in the breast or that has spread to nearby lymph nodes.”

Regardless of where the cancer cells are found, the cancer is still considered the same type. For instance, breast cancer cells found in lymph nodes outside the breast are still referred to as breast cancer.

Effects of removing lymph nodes

If cancer is found in nearby lymph nodes but hasn’t spread farther, removing those lymph nodes may be your best option. But without those lymph nodes to drain lymph fluid, that fluid can build up and lead to swelling called lymphedema.

The more lymph nodes that are removed, the higher your risk of lymphedema.

“Missing lymph nodes doesn’t necessarily affect your immune function because the body has many lymph nodes that can make up for the lost ones,” Dr. Barot says. “The main concern is the potential for developing lymphedema, which is a lifelong condition. If you develop it, your care team will work with you to manage it and make sure that you feel as comfortable as possible.”

When to see a provider for swollen lymph nodes

Your lymphatic system plays a big role in your immune system, so it’s common to notice swollen or hardened lymph nodes. This typically means your body is responding to:

• An infection or virus
• Inflammation
• A recent vaccination

If you also have other symptoms, like congestion and a cough, there’s a good chance the immune cells in your lymph nodes are battling a respiratory virus. This type of swelling should go down within two weeks, but if it doesn’t, see a healthcare provider.

Swollen lymph nodes that happen for no obvious reason and with no other symptoms are a bigger concern.

“For example, cancer that starts in areas like the ovaries can sometimes spread to nearby lymph nodes like your groin, or to distant lymph nodes like those near your collarbone,” Dr. Barot explains.

“This may be one of the first signs of cancer. While these situations are rare, it’s always important to have any new or worsening symptoms checked by a healthcare provider.”