Dear seven7: When doctors do mastectomy with lymph node dissection, the lymph nodes that are removed are contained in a portion of tissue called the "fat pad." The number of lymph nodes in this tissue can vary widely (15 is an average number). There are additional lymph nodes in the under arm but these are not removed because you need them for lymphatic drainage. There is no guarantee that all the remaining nodes are free of disease. It only means that of the 15 removed, 14 are positive. The chemotherapy is designed to address any remaining cancer cells. This new staging will have absolutely no impact on your current treatment. You are getting the gold standard therapy by my estimation.