Total Mastectomy is the removal of the breast. In most cases, mastectomy is required in order to remove cancerous tissue from the body. The extent of tissue removed is determined by the amount of cancer present in your body. Patient Education A total mastectomy involves the removal the breast, but not the removal of lymph nodes or chest muscle that lies underneath the breast. Your doctor has recommended that you undergo a total mastectomy because the cancer in your breast has progressed to the point that it is in danger of spreading into other parts of your body and the only way to make sure that all of the disease has been eliminated is to remove the entire breast. This is major surgery and the procedure will permanently change the outward shape and appearance of your chest. So make sure that you ask your doctor to carefully explain the reasons behind this recommendation.