If breast cancer spreads, it usually goes to the lymph nodes first. So when a woman is diagnosed with breast cancer, it’s important to know if it’s already spread to the lymph nodes.
There are thousands of lymph nodes in the body. They are usually tiny, about the size of a grape seed or maybe a watermelon seed, and we ‘re usually not even aware of them. Lymph nodes have several jobs:
In the axilla (underarm or arm pit) there are about 30 or 40 lymph nodes on each side, everyone is a little different. If a cancer cell or clump of cellsbreaks off the main tumor it is usually (but not always) taken up by one of the lymphatic vessels in the breast.The lymphatic vessels form a network and drain (for the most part) into the lymph nodes located in the axilla on the same side as the breast (ipsilateral axillary lymph nodes) where they are trapped. Sometimes the lymph node kills the cancer cells (way to go lymph node!) but other times the cancer cells are able to resist the lymph node and multiply (tricky cancer).
Cancer cells can also spread through the blood vessel and bypass the lymphatic vessels, but this is less common.
It’s important to understand that, although it seems counter intuitive, removing malignant lymph nodes in a patient whose lymph nodes appear normal on physical examination and imaging, does not to improve survival.
The reason we remove axillary lymph nodes is to accurately stage a patient and plan treatment.
In the body, a vessel refers to soft, flexible tube that carries some sort of fluid.
There are 2 types of vessels:
Axillary lymph nodes can be seen on mammogram (partially), ultrasound (sonogram) and MRI (magnetic resonance imaging). So they can be evaluated preliminarily with imaging. If a lymph node looks abnormal on imaging, it can be biopsied it with a needle.
Keep in mind that just because the lymph nodes look normal on imaging, doesn’t mean they don’t contain cancer cells. That’s because ten, a few hundred, or a few thousand cancer cells will not change the appearance of a lymph node on imaging orto the human eye. Small amounts of cancer like that can only be seen with a microscope.
So if the lymph nodes look normal on imaging or if a lymph node is biopsied and cancer cells are not seen, it’s still necessary to go the extra step and remove the whole lymph node and look at it under the microscope to determine whether or not it contains cancer.