Dear Suina: Both new primary breast tumors and tumor recurrences can occur after breast conservation surgery. Whether it is a new primary depends upon the histology (how similar to the original tumor under a microscope) and the location in the breast (is it close or distant to the original tumor). In most cases, mastectomy would be recommended. Treatment and prognosis would be based upon the histology, size of the tumor, hormone receptors, lymph node status, etc. Your doctor will be best equipped to discuss this as it pertains to your situation.