The lymphatic system is one of the body’s primary tools for fighting infection. This system contains lymph fluid and lymph nodes, which occur in critical areas in the body. Cancer cells sometimes enter and build up in the lymphatic system.

Lymph nodes are small structures inside the body that connect to a network of lymph vessels. Lymph nodes are responsible for filtering lymph fluid. They also detect chemical changes that signal an infection is present. The lymph nodes in the armpits are called axillary lymph nodes.

Axillary lymph nodes are located near the breasts. This means they are often the first location to which breast cancer spreads if it moves beyond the breast tissue.

The number of axillary lymph nodes can vary from person to person. Typically, a person has 20–30 axillary lymph nodes.

After a breast cancer diagnosis, a doctor may check whether cancer cells have spread to the axillary lymph nodes. This can help confirm the diagnosis and staging of cancer.

This article will look into the link between breast cancer and the axillary lymph nodes, as well as treatments and outlook.

Map of lymph nodes near breasts.Share on Pinterest
Medical Illustration by Bailey Mariner

When a person has cancer, it can metastasize, or spread, to other parts of their body. Cancer spreads when part of the tumor breaks off and travels to other parts of the body.

Cancer cells may travel in the bloodstream or through the lymphatic system. Cancer that travels via the lymphatic system may end up growing inside the lymph nodes.

Axillary lymph nodes are in the armpits, which are close to the breasts. Because the axillary lymph nodes are so close, breast cancer usually spreads to them before other lymph nodes.

If cancer has spread to the axillary lymph nodes, a doctor may recommend removing some or all of the lymph nodes during a mastectomy. A mastectomy is a surgical procedure that removes one or both of a person’s breasts.

Lymph nodes are responsible for draining lymph fluid. As a result, removing them can cause some side effects after surgery. One possible side effect is lymphedema of the arm, which causes a type of chronic swelling.

General symptoms of metastatic cancer include:

  • loss of energy
  • tiredness or weakness
  • unintentional weight loss
  • pain
  • shortness of breath or trouble breathing

According to Cancer Research UK, symptoms of breast cancer that has spread to the axillary lymph nodes can include:

  • a lump or swelling in the armpit
  • swelling of the arm or hand
  • a lump or swelling in the breastbone or collarbone area

If a person notices any of these symptoms, they should speak with their doctor as soon as possible.

When checking whether breast cancer has spread to the axillary lymph nodes, a doctor may perform a physical examination or a scan such as an ultrasound, MRI, or CT. During a physical exam, a doctor may check a person’s armpits for swelling.

A scan may be able to detect changes in the lymph nodes, such as:

  • thickening inside the lymph node
  • an increase in blood vessels
  • the loss of hilum, the structure where lymph vessels exit the node
  • the loss of a kidney-shaped appearance

According to some estimates, laboratory tests find cancerous nodes in one-third of females who test negative during a physical exam. This means further testing is essential in most people.

A doctor can use several diagnostic methods to determine whether cancer has spread to the axillary lymph nodes:

Sentinel node biopsy

A sentinel node biopsy involves injecting a radioactive substance or dye into the breast. The dye will move to certain lymph nodes before others.

A doctor can use imaging to identify the sentinel lymph nodes, which are the lymph nodes that the dye reaches first.

A doctor removes one or more sentinel nodes and sends the sample to a pathologist. This method can help a person avoid the side effects of removing multiple axillary lymph nodes.

If the pathologist finds cancer in the sentinel nodes, a person may need to have more lymph nodes removed.

Axillary dissection

Axillary dissection is a procedure that involves removing additional lymph nodes from under the armpit. The purpose of this is to check for cancer spread and to lower the chance of cancer redeveloping in the lymph nodes.

The doctor removes an area of fat that contains many or all of the lymph nodes. The number of lymph nodes removed can vary but generally ranges from 5–30. Once the doctor removes the nodes, a pathologist can determine whether cancer has spread beyond the sentinel lymph nodes.

Staging

Cancer stages indicate the extent and spread of the disease. Knowing the stage can help a doctor determine a person’s outlook and treatment plan.

Doctors use the tumor, nodes, and metastasis (TNM) system to work out the stage of breast cancer:

  • The tumor staging defines the size of the original tumor.
  • The node staging tells whether breast cancer has reached the lymph nodes and how many nodes show signs of cancer cells.
  • The metastasis staging gives information on whether cancer has spread to other parts of the body from its site of origin.

The node staging has several subcategories to provide more specific detail:

NX: There is no information about the nearby lymph nodes, or assessment of the axillary lymph nodes is not possible. For example, a person may have already undergone surgery to remove them.

N0: Cancer has not spread to the lymph nodes. However, a doctor may request further testing to see whether microscopic amounts of cancer cells are present in the lymph nodes. These cells are known as micrometastases.

N1: Micrometastases or cancerous cells are present in 1–3 axillary lymph nodes or the nodes inside the breast.

N2: In this stage, 4–9 axillary lymph nodes have cancerous cells. A doctor also uses this stage to indicate that the nodes inside the breast have developed cancer. These nodes are known as internal mammary nodes.

N3: This stage can indicate a range of outcomes, such as:

  • Testing found cancer in 10 or more axillary lymph nodes.
  • Cancer is in the lymph nodes under the clavicle, or collarbone.
  • Cancer is in the internal mammary nodes and one or more axillary lymph nodes.
  • Four or more axillary lymph nodes are cancerous, and internal mammary nodes have micrometastases.
  • Testing found cancerous nodes above the clavicle.

The staging of axillary lymph nodes becomes higher when cancer has spread to more nodes. Cancer staging also increases as the cancer affects different types of nodes.

Learn how quickly breast cancer can spread in 1 year.

Breast cancer treatment often requires a mastectomy, which is the removal of one or both breasts. An alternative is a lumpectomy, which is the removal of the tumor and surrounding tissue.

The American Cancer Society notes that people who have surgery for breast cancer usually have radiation therapy as well. Radiation therapy is a treatment that uses radiation to kill cancer cells, lower the chances that cancer will come back, and help people live longer.

Most people with breast cancer in stage I, II, or III will receive drug therapy to prevent the cancer from spreading. Drug therapies for breast cancer include:

The amount of treatment a person needs will depend on how far their cancer has spread, their personal preferences, and other factors.

When cancer spreads from its starting point, it can become harder to treat. If breast cancer spreads to the axillary lymph nodes, the outlook becomes worse.

Other factors that can affect the outlook include:

  • the overall size of a tumor
  • the type of cells present
  • whether cancer has spread to other organs
  • a person’s overall health and medical history

A 5-year survival rate is the likelihood that a person will still be alive 5 years after diagnosis.

According to the American Cancer Society, breast cancer that has spread to nearby lymph nodes has a 5-year survival rate of 86%. However, if a person’s breast cancer spreads to other parts of their body, the 5-year survival rate decreases to 29%.

Cancer cells can travel from the breast via the lymphatic system. This may result in a person developing cancer in their axillary lymph nodes. When this happens, a person may notice a lump or swelling in their armpit, breastbone, or collarbone.

A doctor can use various diagnostic tests to determine whether a person’s breast cancer has spread to their lymph nodes. If the cancer has spread, a surgeon may remove a person’s lymph nodes. Doctors also prescribe radiation therapy and drugs to treat breast cancer.

If a person notices any symptoms of breast cancer spreading to their axillary lymph nodes, they should speak with their doctor as soon as possible. Early diagnosis can make cancer easier to treat.

Q:

Does breast cancer spread to lymph nodes outside of the armpits?

Anonymous

A:

Breast cancer can spread to any lymph nodes. Most often, it spreads first to the axillary lymph nodes (in the armpit) and then to the clavicular nodes (in the collarbone) or internal mammary nodes (in the breast).

Yamini Ranchod, PhD, MSAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

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