Breast cancer can spread through lymph vessels , to structures called lymph nodes, which are present in the axilla. Lymph is a clear-to-white fluid, unlike our red coloured blood, and is responsible for carrying white blood cells that provide protection to our bodies against bacterial infections. This lymph is filtered in the lymph nodes, which are located in various areas of the body, one of which is the axilla or armpit. They are also present in the neck, which you can feel when you have tonsillitis. These nodes are a part of our immune system and there is always a possibility that the tumour in the breast will spread to the axillary nodes. Removal of tumour from the axilla has neither been easy nor free of lasting damage. In the past, women not only underwent mutilating breast surgeries or total mastectomies, but also endured radical surgeries to remove all the nodes from the axilla. And with the axilla having 40-50 nodes, one can only imagine how precise and careful the surgery had to be done.
However as of today, there has been tremendous change in the recommendations for handling the axilla. There have been major studies to identify a single node in the axilla. This node is called the sentinel node, also referred to as the watchman of the axilla. The significance of this node is that it is the first lymph node to encounter cancer cells. Therefore, identification of this node allows quick biopsy and accelerated diagnosis.
Sentinel node biopsy is performed during the same surgery on the breast. This process involves injection of a radioactive nuclear dye in the breast under the areola. This dye travels through the lymphatic system, first into that single node, that is, the sentinel node. The sentinel node is then identified with a special instrument called the (gamma camera picks up the radioactive dye containing lymph node) It is then biopsied and sent to a histopathologist, who provides the diagnosis within 15 minutes.
This technique is useful because, if the node is diagnosed as negative, it would mean that the patient has no disease, thus saving her from extensive surgery where the rest of the nodes would have to be removed. And being a biopsy, it is painless as well as scarless, therefore the patient neither bears scars, nor has to undergo surgery.