Repair of the Partial Mastectomy Defect with Staged-Immediate Free Tissue Transfer

Introduction

Over the last two decades breast-conserving treatment (BCT), consisting of breast-conserving surgery (BCS), radiation therapy (RT), and axillary node sampling, is emerging as the treatment of choice for many women diagnosed with early-stage breast cancer. The aptitude to remove only the necessary amount of breast tissue, leaving as much native breast tissue and skin as possible and judicially leaving the nipple–areola complex (NAC) intact, has revolutionized modern-day treatment of breast cancer. BCT offers women diagnosed with breast cancer the opportunity to maintain the overall breast shape as well as cosmetic, functional, and psychosocial advantages.

Modern prospective studies with follow-up times of up to 20 years have compared mastectomy with BCS and RT for the treatment of early-stage breast cancer (stage I and stage II) and have consistently shown no significant differences in overall or disease-free survival when comparing the two treatments. Furthermore, in recent years a definite reduction in local recurrence rates, with numbers comparing favorably with mastectomy, is achieved using BCT due to more accurate mammographic and pathologic evaluation and, more importantly, the widespread use of systemic therapy. Randomized trials comparing BCT and mastectomy demonstrated similar local recurrence rates, 5.9% versus 6.2%, respectively, and in the more recent trials in which all patients were treated with adjuvant chemotherapy, the 10-year local recurrence rates were lower than 5%.

The growing number of BCT procedures being performed challenges the creativity of the oncoplastic surgeon occasionally confronted with complex three-dimensional partial defects. Reconstruction of partial breast defects resulting from BCT can be broadly categorized into volume displacement techniques versus volume replacement techniques. As a general rule, the ratio of breast mass excision relative to the initial breast volume will assist in choosing between volume displacement and replacement.

Frequently larger breasts (cup C and larger bra size) with smaller excisions are amenable to a variety of described techniques that either reduce and/or rearrange the remaining breast tissue and skin envelope. Often in these situations, manipulation of the contralateral unaffected breast is also required to achieve symmetry. A more challenging task, however, is the partial reconstruction of smaller breasts (cup A and B bra size), which will often require the replacement of volume.

Implementing our gained knowledge with free flap breast reconstruction of total mastectomies utilizing the deep inferior epigastric perforator (DIEP) flap and superficial inferior epigastric artery (SIEA) flap, our group has been performing staged-immediate partial breast reconstruction with mini-SIEA and mini-DIEP flaps. Guided by the rationale of minimizing donor site morbidity while still giving the best reconstructive result we can offer, we believe the abdominal tissue is the most appropriate volume replacement source for our partial free flap reconstructions. We refrain from adding unnecessary scars on the breast and avoid the unsightly back scars, both associated with other techniques.

Although we view the abdominal tissue as the donor site of choice, in cases in which this tissue is unavailable other options exist for free flap reconstructions such as the superior or inferior gluteal artery perforator flaps (SGAP and IGAP), the transverse upper gracilis flap (TUG), and the anterolateral thigh flap (ALT), all of which have mainly been described for total mastectomy reconstruction.

Losken et al published their experience with immediate endoscopic latissimus dorsi flap reconstruction of partial mastectomies at the time of tumor excision based upon initial gross or frozen section analysis. They conclude that although staging the excision and reconstruction raises the cost of initial care, its cautious use might be warranted by the capability to increase patient selection for BCT and improve aesthetic results while preserving oncologic safety. At our institute we postpone the reconstruction until final pathology reports confirm wide negative margins. Reconstruction is staged 7–14 days after initial tumor excision (staged-immediate reconstruction).

The most important aspect when comparing immediate versus delayed reconstruction is the timing of RT. Previous experience with immediate reconstructions of total mastectomies with free flaps and RT has notoriously produced unsatisfactory cosmetic results because of the adverse effects of RT on flaps. In total mastectomy reconstruction, this has led surgeons to defer the reconstruction to a delayed stage.

Contrary to total mastectomies, we have found the effect of RT on mini-flaps to be minute. In fact, even though we recommend harvesting mini-flaps 20% larger as a preemptive measure against flap contracture due to RT effects, we consistently find the flaps to tolerate RT very well and suffer minor contracture, if any (as can be seen in the representative case in Figs 10.1–10.7 ). We attribute the hardiness of mini-flaps to two main factors: first, mini-flaps are essentially smaller flaps that mainly comprise the zone I vascular territory. This produces a higher relation of what we refer to as vascular perfusion territory to flap tissue ratio, meaning hardier perfusion per tissue weight.

Second, the RT protocols for total mastectomies versus partial mastectomies are different; the amount of total radiation energy is less in BCT, and usually does not include a boost. Thus, logically, the damage to the flap itself and surrounding skin is expected to be much smaller in partial mastectomies.

In our institute the RT protocols are as follows:

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BCT: 4500 cGy in 25 fractions with a daily dose of 180 cGy; patients occasionally receive boost.
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Total mastectomy: 5040 cGy in 28 fractions with a daily dose of 180 cGy; patients receive boosts of 200 cGy for a total of 1000 cGy in five fractions.

The advantages of staged-immediate reconstruction with mini-flaps are:

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Operating in a non-irradiated field with hardier tissue perfusion and no post-irradiation fibrosis and scarring.
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Immediate positioning of the flap provides a scaffold and minimizes skin contracture and breast tissue collapse that is often seen in delayed reconstruction, thus simplifying the accurate recreation of the excisional defect and more precise flap tailoring.
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A smaller skin island is required, which in most cases can be reduced or even completely removed at a later stage.
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Diminishes psychological distress from the partial mastectomy, shortening the time period the patient has to live with the excisional deformation.
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Improved cosmetic result in breast contour and skin sensation.
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Improved sensation and positioning of the nipple areola-complex.

Indications, contraindications, and patient selection ( Table 10.1 )

One of the most important factors in patient selection is the patient’s desire to preserve native breast tissue, principally the NAC. Patients showing high motivation towards conservation therapy will be more willing to undergo a more extensive free tissue transfer of a muscle-preserving flap, accept the unavoidable donor site scar, comply with the pre- and postoperative instructions, and most importantly, conform to the needed periodic physical and mammographic evaluations.

Table 10.1

Indications and contraindications for patient selection

Indications	Contraindications
Stage I, II breast cancer Small–medium-sized breast Remaining breast is negative for suspicious lesions per MRI Patient motivated to undergo BCS and RT Patient willing to continue with periodic radiological follow-up Slightly elevated BMI with excess abdominal tissue Negative microscopic tumor margins	Advanced-state breast cancer BRCA 1 and BRCA 2 positive patient Suspicious MRI findings Unfavorable cancer oncotype Active smoker Concomitant high-risk surgical morbidities Positive microscopic tumor margins

One aspect in which partial breast reconstruction is different from total mastectomy reconstruction is the amount of tissue needed for reconstruction. The amount of excess abdominal tissue required is usually much smaller in partial reconstructions; hence the ideal patient need not have large amounts of excess abdominal tissue. Owing to the design of the mini-SIEA and mini-DIEP flaps, the ideal body habitus should be normal to slightly elevated body mass index (BMI), and mild to moderate lower abdominal wall laxity, as is often seen after pregnancies.

In our experience, patients perceive the sacrifice of lower abdominal tissue as an added cosmetic bonus to their cancer treatment and are willing to accept the well-hidden lower abdominal scar. Frequently, the lower abdominal scar is merely an extension of an already existing Pfannenstiel scar. Several studies have demonstrated high patient satisfaction rates with abdominal contour subsequent to lower abdominal perforator flap harvest for breast reconstruction.

Exclusion criteria include patients with advanced-stage cancer, BRCA 1 and BRCA 2 positive patients, large-breasted women (cup D or larger bra size), very thin patients with no abdominal tissue excess or redundancy, suspicious magnetic resonance imaging (MRI) findings, positive microscopic tumor margins, and concomitant high-risk surgical morbidities.

The following is a list of relative contraindications we use for all our free tissue transfers to the breast: active smoking history, age greater than 60 years, BMI greater than or equal to 35 kg m ⁻², prior abdominal surgery with extensive scarring, prior abdominal liposuction, and coagulation disorder.

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