In breast cancer patients undergoing partial mastectomy, surgical margins help determine future treatment. Because positive surgical margins are associated with an increased risk of local recurrence and, consequently, systemic disease, the primary goal of partial mastectomy is to remove the tumor with a negative microscopic margin. The primary goal of partial mastectomy in the operating room is to remove the cancer with an envelope of normal tissue around it to obtain negative margins (i.e., to achieve
an R0 resection; see Fig. 1-1) while maintaining optimal breast cosmesis. In the operating room, surgeons must be cognizant of encompassing the tumor with normal tissue around it. For patients with tumors involving the skin and/or chest wall, en bloc resection that includes the overlying skin and/or underlying muscle should be performed. The oncologic safety of breast conservation has been proven over many years, multiple randomized studies having shown that local recurrence rates following lumpectomy with negative margins plus radiotherapy are significantly lower than those following lumpectomy with a positive margin plus radiotherapy.

The width of negative surgical margins necessary to minimize local recurrence in patients undergoing breast cancer surgery, including partial mastectomy, remain controversial. The National Surgical Adjuvant Breast and Bowel Project has long taken the position that unless tumor cells are immediately adjacent to the inked surface of the lumpectomy specimen, no further excision is needed. Long-term results of this approach and recurrence rates have been published.¹

For example, the B-06 study, which randomized patients to lumpectomy alone versus lumpectomy plus radiation versus total mastectomy, has shown acceptable local recurrence rates with lumpectomy plus radiation compared to mastectomy with a greater than 20-year follow-up. Other randomized prospective trials from the National Cancer Institute, Veronesi et al, and the European Organization for Research and Treatment of Cancer (trial 10801) have shown similar results, reporting 5-year local recurrence rates of about 10% for patients who undergo lumpectomy with no tumor at the inked margin plus radiotherapy.²,³,⁴ Unfortunately, these trials’ findings are inconclusive, as the investigators did not know whether the surgeons resected additional tissue in cases involving “close” margins or “ink on tumor.” Some thoughtful meta-analyses suggest that obtaining margins greater than 1 mm does not improve rates of local control.⁵,⁶,⁷ Regardless, virtually all studies investigating surgical margins in breast cancer surgery
have shown that patients in whom positive margins are retained have higher recurrence rates than do patients in whom negative margins are achieved.⁸ A recent consensus statement from the Society of Surgical Oncology and American Society of Radiation Oncology concluded, “The use of no ink on tumor as the standard for an adequate margin in invasive cancer in the era of multidisciplinary therapy is associated with low rates of ipsilateral breast tumor recurrence and has the potential to decrease re-excision rates, improve cosmetic outcomes, and decrease health care costs.”⁹,¹⁰ Critics of this meta-analysis comment that the majority of the studies used were retrospective and details about adjuvant treatment were lacking, including radiation. Some surgeons still advocate a more individualized approach. When making decisions about treatment after lumpectomy, the care team should carefully consider the final pathologic assessment of surgical margins in a multidisciplinary fashion.¹¹

Most breast cancers, many of them nonpalpable, are detected by radiographic screening such as mammography. These nonpalpable lesions require image-guided localization to help maximize the likelihood that negative surgical margins will be achieved. Image-guided tumor localization is guided by the modality used to detect the tumor: mammography,¹² ultrasonography,¹³ or magnetic resonance imaging¹⁴ (Fig. 1-2). For lesions that span a large area (a large segment of malignant calcifications), bracketing the area by the use of wires or other markers to delineate the area improves the likelihood that the surgeon is able to completely remove the targeted lesions.¹⁵

The most commonly used modality for image-guided tumor localization is wire localization. Despite its very high success rate, wire localization has several drawbacks, including a high positive margin rate,¹⁶ wire migration,¹⁷ wire transection,¹⁸ and surgery scheduling issues because it is performed on the same day, limiting the times and number of procedures performed per day. Alternatives to wire localization (see Fig. 1-2) include radioactive seed localization (RSL),¹⁹ radioguided occult lesion localization (ROLL),²⁰ and intraoperative ultrasonography localization. Retrospective studies have shown that these techniques can decrease the volume of tissue excised and the rate of positive margins.²¹ Single-center institutional series and small randomized trials have shown that, in experienced hands, these techniques can be used to delineate tumors with an accuracy similar to that of wire localization and may have positive margin rates that are lower than that of wire localization.²²,²³,²⁴,²⁵,²⁶,²⁷ Regardless of the method of localization, the tumor targeted
for excision must be documented by specimen radiography²⁸,²⁹ (see Fig. 1-3). Even for palpable lesions, where the surgeon’s physical examination guides the location of the incision and the amount of tissue to be resected, the use of intraoperative ultrasonography has been shown to decrease the volume of tissue excised and the rate of positive margins.³⁰,³¹

The use of intraoperative imaging to confirm the resection of nonpalpable lesions has been the standard of care for the last 10 years. In 2001 (and again in both 2005 and 2009), the Image-Detected Breast Cancer: State-of-the-Art Diagnosis and Treatment Consensus Panel made the following recommendation:

In addition, multiple retrospective studies have shown that the positive margin and re-excision rates of cases in which intraoperative imaging has been performed are lower than those of cases in which intraoperative imaging has not been performed.³³,³⁴
In addition, investigators who have examined the utility of the RSL technique have recommended that even in cases in which radioactive seeds have been utilized for tumor localization, specimen radiography is needed to confirm that the marker clip and seeds have been removed with the specimen.³⁵ Finally, the American Society of Breast Surgeons recommends that specimen radiography or specimen ultrasonography be performed routinely during the excision of abnormalities detected with imaging studies to document the removal of the target lesion.³⁶

Specimen orientation at the time of excision enables the pathologist to replicate the specimen’s anatomical position during pathologic evaluation. For consistency in reporting and communication, the surface of the lumpectomy specimen is commonly delineated into superficial, deep, superior, inferior, medial, and lateral sides. The orientation method that is least equivocal and most likely to minimize discordance between surgery and pathology settings appears to be intraoperatively marking each of the six sides of the specimen with inks or paints of different colors immediately following resection (Fig. 1-4).
Another option for specimen orientation is to use three sutures to mark the anterior, lateral, and superior sides of the specimen. Specimen orientation with two sutures, which has been reported to result in high rates of discordance between surgery and pathology settings, is not recommended. The recommendation to use three rather than two sutures is primarily based on the findings of a limited prospective analysis of specimen disorientation using the two-suture technique and a retrospective analysis of intraoperative inking versus standard postoperative inking after initial orientation using the three-suture technique.³⁷ Most surgeons rely on the final postoperative pathologic evaluation for final margin assessment in order to decide whether additional tissue must be removed. Regardless of whether the pathologist examines the specimen during or after surgery, reliable specimen orientation is required to facilitate the decision to remove additional tissue of specific margins.³⁸,³⁹

Clip placement in cases where oncoplastic techniques are utilized for immediate reconstruction is essential due to the uncertainty about the location of the excision cavity that can affect the targeting of breast irradiation, as well as the radiation boost delivered as part of whole-breast radiotherapy. Oncoplastic techniques often require that breast tissue adjacent to the tumor bed be detached from the pectoralis major muscle and mobilized to close the excision cavity and subsequently results in little or no seroma formation, making it difficult to visualize the lumpectomy cavity at the time of radiotherapy planning. In addition, because the breast tissue is rearranged, the position of the tumor bed may shift, further complicating radiotherapy planning.³⁹ Furthermore, the surgical scar is a poor indicator of the location of the excision cavity and cannot be reliably used to direct radiotherapy planning. The placement of surgical clips for the localization of the lumpectomy cavity after tumor resection and before breast reconstruction facilitates the accurate delivery of radiation to the tumor bed (Fig. 1-5).

Movement of the tumor bed owing to immediate breast remodeling after lumpectomy is not uncommon. In one retrospective study, the tumor bed, which had been marked with surgical clips, had extended beyond its original breast quadrant or had migrated completely to a different region in 8 (73%) of 11 patients at the time of
radiotherapy planning.⁴⁰ In another study evaluating 50 patients’ radiation target field plans, which were based on surgical clip location, simulations revealed that the absence of surgical clips would have resulted in inadequate radiation doses in tangent fields in 4 (8%) patients and totally or marginally missed radiation boost targets in 23 (46%) patients.⁴¹ Placing surgical clips provides a reliable means of delineating the tumor bed. In a study of 40 breast conservation patients, breast irradiation plans revealed that, compared with no surgical clip placement, the placement of surgical clips at the four cardinal points of the lumpectomy cavity resulted in a higher conformity index of tumor bed delineation and less interobserver variability among radiation oncologists.⁴² Another study of 30 patients demonstrated that the relative positions of the implanted surgical clips remained consistent throughout the course of radiotherapy.⁴³