Shave: A Randomized Controlled Trial Of Routine Shave Margins Versus Standard Partial Mastectomy.

TPS1145 Background: It is well known that partial mastectomy for breast cancer is associated with a positive margin rate of 20-40% in most series. This has led some surgeons to advocate for routine cavity shave margins as a means of reducing re-excision rates. Others, however, feel that such a practice may be unwarranted and question the volume of tissue removed, cosmetic outcome and increase in operative time. It is unclear which of these two approaches is optimal; therefore, a prospective randomized controlled trial was proposed. Methods: Given the primary endpoint of positive margin rates (defined as a margin of < 1mm), the study was powered to find a difference between 30% in the standard partial mastectomy group and 15% in the routine shave margin group. To reach a power of 80% with alpha of 5%, 122 patients were required in each arm; we therefore set N=250 with a 1:1 randomization scheme. Patients are evaluated preoperatively and all patients undergoing a partial mastectomy for stage 0-III breast cancer are eligible; including those who have completed neoadjuvant chemotherapy. Patients are stratified according to stage and randomized within strata. After informed consent, patients undergo a standard partial mastectomy (including specimen radiography as needed). Surgeons may resect additional tissue at that time according to their standard practice. At the completion of this procedure, the randomization envelope is opened in the operating room and surgeons are instructed to either shave (ie., take additional circumferential margins) or close (no shave). Patients will be followed for five years. Outcome measures include: positive margin/re-excision rate, local recurrence, volume of tissue resected, cosmetic outcome, and intraoperative time. To date, over 130 patients have accrued to this trial. Initial results are expected to be reported in 2014. Clinicaltrials.gov identifier: NCT01452399