A re-excision lumpectomy refers to the second surgery some women have when their pathology results come back positive for cancer cells in the margins (the healthy tissue around the tumor that is removed during a lumpectomy). Re-excision means the surgeon reopens the surgical site to remove an additional margin of tissue, with the goal of getting a margin that is cancer-free. Sometimes this practice is called “clearing the margins.” At MSK, our surgeons have been leaders in developing guidelines to spare women from this second surgery in cases where it is not needed.