Lymph nodes are responsible for filtering lymph fluid and detecting chemical changes that signal if an infection is present.
Cancer cells can also get into the lymphatic system and get lodged in lymph nodes. When they are in the armpit, these filter points are called axillary lymph nodes.
- When cancer has spread to the axillary lymph nodes, the nodes may feel enlarged, or there may be a noticeable lump.
- A breast cancer prognosis is better when the cancer is only in the breast, and the lymph nodes are not affected.
- Most people who have enlarged axillary lymph nodes do not have cancer at all.
- The staging or grading of cancer takes into account whether and how much cancer has spread to the lymph nodes.
Axillary lymph nodes and breast cancer
Sometimes, breast cancer can spread to the axillary lymph nodes, which are in a person's armpits.
The number of axillary lymph nodes can vary from person to person, ranging from 5 nodes to more than 30.
When someone is diagnosed with breast cancer, knowing if cancer has spread to their axillary lymph nodes can determine the type of treatment they have, as well as their prognosis.
What's the connection?
Knowing whether cancer has spread to the axillary lymph nodes can impact both treatment and prognosis.
The axillary lymph nodes are usually the first set of lymph nodes where breast cancer will spread.
And because the breast and armpit are close to each other, the lymph nodes are a common place where this type of cancer spreads.
As a general rule, the more a cancer has spread from its starting point, the worse the prognosis may be for a person.
Also, if the cancer has spread to the axillary lymph nodes, a doctor will usually recommend removing the lymph nodes during the surgery to remove the originating tumor.
Lymph nodes are responsible for draining lymph fluid, so their removal can cause some side effects after surgery. One side effect can be lymphedema of the arm, which is a chronic swelling of the arm.
Axillary lymph nodes often feel like small, round "sponges" under the skin. Sometimes they are painful to the touch. A doctor will investigate if the cancer may have spread to the lymph nodes by doing a physical examination.
The doctor will feel around the collarbone and neck for signs of enlarged lymph nodes, as well as underneath the arm.
According to the Susan G. Komen Breast Cancer Foundation, one-third of women who do not have lymph nodes that can be felt in a physical exam are found to have cancerous lymph nodes after further testing. As a result, it is usually vital to conduct more testing after the initial physical exam.
A doctor has several different diagnostic methods to determine if the cancer has spread to the axillary lymph nodes. These include:
Sentinel node biopsy
A sentinel node biopsy involves injecting a radioactive substance or dye into the breast. A doctor will then use imaging to identify the lymph nodes the dye goes to first. These first lymph nodes are known as the sentinel lymph nodes.
A doctor will remove one and send it to a pathologist who specializes in identifying types of cancerous cells. This approach can save a person from the side effects of removing multiple axillary lymph nodes.
According to the Susan G. Komen Foundation, sentinel node biopsy correctly predicts the status of further lymph nodes in 96 percent of women with breast cancer.
Axillary dissection is a procedure that involves removing more lymph nodes under the armpit. This is done by removing an area of fat that contains many or all of the lymph nodes. A doctor will then test these for cancer to determine if it has spread beyond the sentinel lymph node and, if so, how far it has spread.
After surgery, sometimes the lymph nodes are radiated along with breast radiation to target any possible remaining cancer cells.
A doctor will check for signs of enlarged lymph nodes around the collarbone and neck.
The staging of a person's cancer is a part of the TNM system, which stands for Tumor, Nodes, and Metastasis.
Some doctors use the TNM system to help them provide a prognosis or an outlook for how likely they are to be able to treat a person's breast cancer successfully.
The N staging categories include:
- NX: Axillary lymph nodes cannot be assessed, for example, if they were previously removed.
- N0: Cancer has not spread to the lymph nodes. However, a doctor may choose to perform other types of tests to determine if 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 to 3 axillary lymph nodes, or the internal mammary nodes have tiny amounts of cancerous cells.
- N2: In this stage, 4 to 9 axillary lymph nodes have cancer present, or the internal mammary nodes have cancer
- N3: This stage has a broad spectrum, as follows:
- cancer has been found in 10 or more axillary lymph nodes
- cancerous lymph nodes are found under the clavicle
- internal mammary nodes have cancer plus one or more axillary lymph nodes are cancerous
- four or more axillary lymph nodes are cancerous and internal mammary nodes have micrometastases
- cancerous nodes are detected above the clavicle
The more nodes and types of nodes involved, the higher the staging category for axillary lymph node status.
The prognosis is poorer when a person's cancer has spread to their lymph nodes, especially when it has spread to more of these.
However, lymph node staging is only one piece of the puzzle for cancer prognosis.
A doctor will also consider the overall size of a person's tumor, the type of cells present, and if the cancer has spread to other organs.
These factors and other considerations, such as a person's overall health and medical history, can further affect the prognosis they will receive.