Lymph nodes are small, bean-shaped organs of the immune system, part of the lymphatic system. They filter waste and foreign substances from the body and are found throughout, including the neck, armpits, and groin.
Understanding Breast Lymph Nodes
Lymph nodes are structures that act as filters within the lymphatic system. They contain specialized immune cells, such as lymphocytes and macrophages, which identify and eliminate foreign invaders like bacteria, viruses, and abnormal cells. These nodes help to cleanse the lymph fluid, a clear liquid that circulates throughout the body, before returning it to the bloodstream.
The breast region has several groups of lymph nodes that drain lymph fluid from the breast tissue. The most common are the axillary lymph nodes, located in the armpit. These nodes, typically 10 to 40, drain about 75-90% of the lymph from the breast.
Other lymph node groups associated with breast drainage include the internal mammary (parasternal) lymph nodes, found near the breastbone, and the supraclavicular and infraclavicular lymph nodes, located above and below the collarbone, respectively. While the axillary nodes are the primary drainage pathway, internal mammary nodes can also be sentinel nodes for breast cancer, particularly for tumors in the medial breast. Intramammary lymph nodes, located within the breast tissue itself, also exist.
Lymph fluid from the breast tissue travels through lymphatic vessels to these regional lymph nodes. As the fluid passes through, the immune cells within the nodes work to trap and destroy any harmful substances. This filtering process is a fundamental aspect of the immune response, helping to prevent the spread of infections or abnormal cells throughout the body.
Their Role in Breast Health
Changes in breast lymph nodes, such as swelling or tenderness, can indicate an underlying health issue. While often benign, like infections or inflammation, these changes warrant medical evaluation.
In the context of breast cancer, the status of lymph nodes is a factor for diagnosis, staging, and treatment planning. Breast cancer cells can detach from the original tumor and travel through the lymphatic system, often reaching the nearest lymph nodes first. The axillary lymph nodes are the most common initial site for breast cancer to spread outside the breast.
When breast cancer cells are found in lymph nodes, it indicates that the cancer has begun to spread, influencing the cancer’s stage. The number of affected lymph nodes can also impact prognosis, with a better outlook if no cancer cells are found in the nodes. Therefore, assessing these nodes is a routine part of breast cancer evaluation.
Doctors assess lymph nodes through various methods, including physical examination, where enlarged nodes might be felt. Imaging techniques like ultrasound, MRI, and CT scans can also help visualize lymph nodes and detect abnormalities. Ultrasound is often the preferred method for evaluating axillary lymph nodes.
A sentinel lymph node biopsy (SLNB) determines if cancer cells have spread to the first lymph nodes draining the breast. A tracer identifies these “sentinel” nodes, which are then removed and examined. If clear, it suggests cancer has likely not spread further, potentially avoiding more extensive lymph node removal. This guides treatment decisions, including additional therapies like chemotherapy or radiation.