Can Routine Cavity Shave Margins (Csm) Improve Local Control In Breast Cancer? Initial Results Of The Shave Trial, A Prospective Randomized Controlled Trial Of Routine Csm Vs. Standard Partial Mastectomy (Spm)

1012 Background: Considerable controversy exists regarding the utility of routine CSM in patients undergoing partial mastectomy for breast cancer. We performed a prospective RCT to determine whether this practice results in a lower positive (+) margin rate. Methods: 251 patients with preoperative Stage 0-3 breast cancer undergoing partial mastectomy were randomized 1:1 to SPM or CSM (80% power to detect a reduction in (+) margin rate from 30% to 15%). Prior to intraoperative randomization, surgeons performed SPM per their usual practice. The sealed randomization envelope was then opened and surgeons were instructed either to take circumferential CSM or close. (+) margins were defined as tumor at ink for invasive cancer, and u003c 1 mm for DCIS. Results: The median patient age was 61 (range; 33-94). 61 (24.3%) had invasive cancer only, 50 (19.9%) had DCIS alone, and 129 (51.4%) had a combination of both. The median invasive tumor size was 1 cm (range; 0-6.5), and median DCIS size was 0.9 cm (range; 0-9.3). The...