What is sentinel node labeling? Can it be done AFTER an excisional biopsy of an invasive intra-ductal solid breast tumor or must this be done before the surgery?
Carolyn Vachani, RN, MSN, AOCN, OncoLink's Nurse Educator responds:
The lymph system's role is to fight infection or invasion by foreign materials in the body. This system runs like a chain throughout the entire body, draining lymph fluid and flushing the body of foreign cells. Unfortunately, cancer cells can use this system as a means to spread in the body. The "sentinel node" is the first node lymph drains to, in the chain closest to the cancer. The theory is that the cancer cell enters a lymph node near the tumor and spreads through the chain, ultimately to other parts of the body (metastasize). By injecting a substance (that can be seen with radiologic tests – usually technetium Tc-99m sulfur colloid, also called a tracer) into the tissue surrounding the tumor, doctors can follow the path the cancer cells would take. Sometimes a blue dye is also used to improve the doctor's ability to see the nodes. The tracer material drains first into the sentinel node, that node is identified, removed and tested for the presence of cancer cells. If the test is positive, then the patient would undergo a complete axillary node dissection to determine how many other nodes are affected. If the sentinel node is negative, then it is thought that the cancer had not yet spread to the lymph nodes and the patient is spared the larger surgical procedure.
To answer the second part of your question, the procedure can be done after a biopsy. After an excisional biopsy, the tracer is injected in the area the tumor was removed from.