Breast cancer is the most common malignancy affecting women in the US. Surgical management is the mainstay of therapy, and in general consists of resection of the primary tumor with either a partial mastectomy (aka "lumpectomy") or a total mastectomy.

The investigators hypothesize that routine shave margins during partial mastectomy will significantly reduce positive margin rate. A positive margin means that cancerous cells were detected at the edge of the excised area. This generally mandates a return to the operating room for re-excision.

Some authors have investigated, in a retrospective fashion, the use of routine shave margins, where surgeons routinely take additional margins at the time of the initial partial mastectomy as a means of obtaining negative margins. While these retrospective studies have found that positive margin rates declined using this technique, opponents to this technique wonder if this truly results in a higher negative margin rate without compromising cosmesis or increasing tissue volume removed. As these studies were retrospective, it was possible that the initial resection was smaller than what those who do not routinely take shave margins would resect. No one had evaluated the impact of further resection on operative time, nor in a blinded fashion, evaluated cosmesis. Further, there had yet to be a prospective study to evaluate the impact of this on local recurrence rates. Hence, the investigators performed a prospective randomized controlled trial of this technique at Yale. The data from this study, published in the New England Journal of Medicine, found that the technique cut positive margin and re-excision rates in half. Some wondered, however, about the external generalizability of these findings, particularly in non-academic settings. Hence, a multicenter trial to validate these findings is warranted.

Inclusion Criteria

1. Breast cancer, stage 0-3, deemed a surgically appropriate candidate for partial mastectomy with planned procedure for the same
2. Women ≥ 18 years of age
3. Ability to understand and the willingness to sign a written informed consent document.

Exlusion Criteria

1. Total mastectomy
2. Known metastatic disease
3. Bilateral synchronous breast cancer
4. Multicentric cancers requiring double lumpectomy
5. Previous history of breast cancer (even in the other breast)
6. Patients receiving Intraoperative radiation therapy (IORT)
7. Patients who had excisional biopsy for diagnosis of their cancer (I.e., instead of a core biopsy)