The direction of lymph flow within the breast tissue is largely toward the lymph nodes in the armpit. For this reason, cancer cells that acquire the ability to spread usually go first to the lymph nodes in the armpit. Knowing the status of the armpit lymph nodes in breast cancer patients is important for diagnosis, treatment and follow-up.
Removal of the armpit lymph nodes applies to tumors that have acquired the ability to spread (invasive). Since in-situ cancers (those that remain limited within the milk ducts) theoretically do not go to the lymph nodes, there is no need to clear the armpit.
Technique: Blue dye (isosulfan blue or methylene blue) is injected, alone or together with a radioactive substance, into the area where the tumor is located or under the nipple. Within 5-7 minutes the dye reaches the first (sentinel) lymph node in the armpit. There may be more than one sentinel lymph node; the average is 2. These lymph nodes are removed and examined for whether they contain tumor cells. If no tumor cells are seen, the procedure is ended; there is no need to remove the other lymph nodes in the armpit.
