The medical term for the armpit is the 'axilla' and axilla surgery refers generally to surgery on the lymph nodes in the armpit, which is common in connection with breast cancer. This is because, if the cancer has spread beyond the breast, the most likely place for it to spread to is the lymph nodes in the armpit. Removal of one or more of these lymph nodes is often performed to check whether this has taken place or not, or in some cases to remove any cancer that is present in the lymph nodes.
If, after examination of lymph node tissue by a pathologist, cancer cells are found, this indicates that there is a chance that cancer has spread into other tissues in the body via the bloodstream. In this case, other non-surgical therapy may be recommended, such as radiotherapy, chemotherapy or hormone therapy.