The direction of lymph flow in the breast tissue is largely towards the axillary lymph nodes. For this reason, cancer cells that spread usually first go to the axillary lymph nodes. Knowing the status of axillary lymph nodes in breast cancer patients is important for diagnosis, treatment and follow-up.

Removal of the axillary lymph nodes applies to invasive tumors. In-situ cancers (confined within the milk ducts) theoretically do not need to be removed from the armpit as they do not travel to the lymph nodes.

Technique: Blue dye (isosulfan blue or methylene blue) alone or in combination with a radioactive substance is injected into the tumor site or under the nipple. Paint 5-7 min. It reaches the first (sentinel) lymph node in the armpit. The number of sentinel lymph nodes can be more than one; the average is 2. These lymph nodes are removed to check whether they contain tumor cells. If no tumor cells are seen, the procedure is terminated; other lymph nodes in the armpit do not need to be removed.