Significant progress has been made in local-regional and systemic treatments of breast cancer. Most patients currently diagnosed with breast cancer in the United States are diagnosed with early-stage disease and achieve excellent outcomes with breast-conservation therapy.

Indeed, outcomes have significantly improved compared to the first generation of trials investigating breast conservation. For example, patients with stage I to II estrogen receptor–positive, HER2/neu–negative disease treated with breast-conservation surgery, breast irradiation, and adjuvant hormonal therapy have in-breast recurrence rates of only 0.5% per year.

Important Concept

An important surgical concept in breast conservation is the resection of gross disease with achievement of negative surgical margins. Over the past 2 decades, there has never been consensus on what represents an optimal negative margin. Some have considered having no tumor present on the inked resection margin to be adequate, whereas others preferred having at least 1 or 2 mm of normal tissue separating the disease and the margin.

Unfortunately, while numerous publications have explored the issue of margin width, there has never been a well-designed prospective trial to investigate this question. Accordingly, individual practitioners have adopted their own standards, resulting in heterogeneous practice patterns across the United States. Many were trained to recommend reexcision for margins within 1 mm or within 2 mm.

These recommendations are made with the hope that they minimize the risk of breast recurrence. However, it is clear that reexcision subjects patients to additional surgery, can affect long-term cosmesis, and increases costs. Management of close margins can also result in more women being treated with mastectomy.

Attempt at Consensus

The recently published Society of Surgical Oncology (SSO) and American Society for Radiation Oncology (ASTRO) guideline on margins for breast-conservation surgery with whole-breast irradiation in stage I and II invasive breast cancer is an excellent attempt to bring some consensus to this topic.¹ The authors of the guideline represented a multidisciplinary panel of experts who critically evaluated the available data and provided consensus recommendations to aid practitioners in their decisions regarding the need for reexcision.

The guideline was recently endorsed by ASCO, as reported in Journal of Clinical Oncology² and reviewed in this issue of The ASCO Post. It is hoped that the guideline can lead to more selective use of reexcision and thereby improve cosmetic outcomes and reduce costs.

It is important for practitioners to appreciate that breast cancer is a biologically diverse spectrum of disease. The most common subcategory of breast cancer is driven by estrogen receptor signaling and, as indicated above, the outcomes for such patients treated with modern-day combined-modality treatment is truly outstanding. For such patients, the costs of routine reexcision of close but negative margins likely outweigh any benefit. However, in less common subsets, such as young patients with triple-negative disease, breast recurrence rates remain at clinically significant levels despite modern multidisciplinary treatment. For situations in which breast recurrence rates remain high, it is still reasonable to consider reexcision of a close margin. ■

Disclosure: Dr. Buchholtz reported no potential conflicts of interest.

References

1. Moran MS, Schnitt SJ, Giuliano AE, et al: Society of Surgical Oncology-American Society for Radiation Oncology consensus guideline on margins for breast-conserving surgery with whole breast irradiation in stage I and II invasive breast cancer. Ann Surg Oncol 21:704-716, 2014; Int J Radiat Oncol Biol Phys 88:553-564, 2014; J Clin Oncol 32:1507-1515, 2014.

2. Buchholz TA, Somerfield MR, Griggs JJ, et al: Margins for breast-conserving surgery with whole-breast irradiation in stage I and II invasive breast cancer: American Society of Clinical Oncology endorsement of the Society of Surgical Oncology/American Society for Radiation Oncology consensus guideline. J Clin Oncol 32:1502-1506 2014.