Safety of Oncoplastic Breast Reconstruction

Introduction

Historically, early stage breast cancer has been treated with either mastectomy or breast conservation therapy (local tumor excision with adjuvant radiation therapy). Clinicopathologic characteristics such as tumor size and extent of breast involvement determine patient suitability for one approach or the other. Landmark prospective studies have shown that these two approaches have equivalent disease-free and overall survival.

Total mastectomy can be a cosmetically deforming and psychologically taxing procedure. Breast reconstruction following mastectomy involves use of prosthetic techniques or harvesting autologous tissue from distant sites to recreate a breast mound. Breast conservation is therefore appealing in its potential to preserve the native breast mound; however, an acceptable cosmetic result is not guaranteed. Up to 40% of patients who undergo breast conservation have had an unacceptable cosmetic result.

Oncoplastic techniques utilize plastic surgical methods of volume displacement and replacement to achieve the primary goal of negative surgical margins as well as the secondary goal of optimal aesthetic result and breast symmetry. Oncoplastic breast conservation has become an increasingly common technique compared with traditional breast conservation over the last 10 years by facilitating reconstruction after larger volume resections. Oncoplastic surgery has greatly expanded the group of patients who may be candidates for breast conservation, and studies using validated questionnaires have demonstrated excellent levels of patient satisfaction. Concerns regarding the oncologic safety of these techniques have increased, mirroring their rising popularity. Safety data pertaining to oncoplastic breast surgery are limited by a lack of prospective data and long-term follow-up.

When discussing reconstructive options with patients, oncologic risks and benefits should be reviewed. With oncoplastic procedures, appropriate patient counseling requires attention to several important clinical questions:

• Do oncoplastic techniques affect the rate of positive margins in breast conservation, and how should positive margins be managed?

• Do oncoplastic techniques affect the rate of local recurrence, disease-free survival, and overall survival?

• Does oncoplastic surgery result in a higher incidence of complications?

• Does oncoplastic surgery affect the delivery of radiation or future surveillance of breast cancer?

In this chapter, the available data to answer these important questions will be reviewed.

Margins in Oncoplastic Surgery

The three goals of breast conservation therapy (BCT) are to remove the primary tumor, decrease breast tumor recurrence, and optimize cosmesis. Positive margins have been clearly shown to be a risk factor for local recurrence, but until recently there was no consensus as to what constitutes a “negative” margin. Based on a meta-analysis of 33 studies reporting on more than 32,000 patients, the Society for Surgical Oncology and American Society of Radiation Oncology released a joint guideline defining a negative margin as “no ink on tumor.” There was no evidence that obtaining a wider margin, such as a threshold of >2 mm or >5 mm, resulted in a lower rate of local recurrence. This recommendation is important when considering an oncoplastic breast conservation procedure, which is often offered to patients with larger tumors who might not be good candidates for standard breast conservation. In a meta-analysis of more than 8500 patients published in 2014, Losken et al compared the outcomes of patients who had undergone standard breast conservation with patients who had undergone immediate breast reconstruction using oncoplastic techniques. They found that, despite overall significantly larger tumor size and lumpectomy specimen weight in the oncoplastic group, the overall positive margin rate was significantly lower in the oncoplastic group compared with the standard breast conservation group (12% vs 21%). An acceptably low positive margin rate following oncoplastic breast conservation has been confirmed in multiple studies, ranging from 0–21% according to a recent systematic review published by Piper et al.

One concern voiced by critics about oncoplastic breast conservation techniques, which utilize volume displacement and parenchymal rearrangement to fill the empty space created by tumor excision, is that the architecture and orientation of the lumpectomy cavity becomes distorted. This has the potential to make identification and re-excision of previous surgical margins more difficult, and in these cases completion mastectomy may be necessary to achieve negative surgical margins. Data from Piper et al suggest that the overall rates of re-excision and completion mastectomy in patients undergoing oncoplastic breast conservation are acceptably low (3.5% and 3.7%, respectively). Despite larger tumor size in patients undergoing oncoplastic breast conservation, available data comparing re-excision and completion mastectomy rates between patients undergoing oncoplastic and standard breast conservation suggest that re-excision of positive margins is less frequently required in the oncoplastic group, whereas completion mastectomy is required at similar rates between the two groups.

Piper et al suggest placement of clips in the cardinal directions of the lumpectomy cavity to both facilitate re-excision in the setting of positive margins and to assist with targeting of the radiation boost. The authors make the argument that, because local tumor recurrence usually occurs in the previous lumpectomy site, marking with clips also allows a second re-excision of breast tissue rather than completion mastectomy in the setting of local recurrence.

A good understanding of factors predictive of margin positivity is necessary to properly counsel patients considering breast conservation versus total mastectomy, as a finding of positive margins after breast conservation will often necessitate additional surgery. In a retrospective review by Clough et al of 272 patients undergoing oncoplastic BCT, the only factor predictive of margin positivity after multivariate analysis was invasive lobular tumor histology. A retrospective review by Amabile et al looking at 129 patients undergoing oncoplastic breast surgery further identified obesity, tumor multifocality, and the presence of microcalcifications on mammogram as predictive of the need for re-excision.

In summary, oncoplastic breast conservation techniques can be offered to patients with acceptable rates of margin positivity compared with standard breast conservation; however, proper patient selection is essential, as margin positivity is one of the primary factors predictive of local recurrence.