Introduction
Breast cancer is the most common cancer in women, with a reported prevalence of more than 3.8 million women in the United States as of January 1, 2019. It is estimated that 268,600 women will be newly diagnosed with breast cancer by the end of 2019. For women with early stage (I or II) breast cancer, the most common treatments are breast-conserving surgery with adjuvant radiation (49%) and mastectomy (34%). For women with stage III disease, mastectomy is the most common surgical treatment (68%).
Breast cancer patients are of great importance to Plastic and Reconstructive surgeons. A national study conducted at Memorial Sloan Kettering found that in 2013, 41% of women who underwent mastectomy received immediate breast reconstruction procedures. That number increased further to 43.3% in 2014. This current reconstruction rate is a significant increase from the previous rate of 18% in 2004. The benefits of breast reconstruction after mastectomy have been well documented, including improved quality of life, body image, psychosocial well-being, sexual well-being, and patient satisfaction.
The two main routes of breast reconstruction involve utilization of either autologous tissue or prosthetic implants. Implant-based breast reconstruction is the most common method of breast reconstruction in the United States, with over 83,000 procedures performed in 2018. This procedure is typically preceded by placement of a tissue expander, which may remain in the breast pocket for up to 3–18 months depending on the need for adjuvant therapies. In traditional breast reconstruction, tissue expanders are used to expand the skin of the breast thereby recreating a breast mound. In addition, a mature retropectoral capsule for the prosthetic implant placement in a second procedure is created. With the advent of the routine use of acellular dermal matrices (ADMs) and skin sparing, along with nipple-sparing mastectomies, the tissue expander allows for controlled recovery of ischemic tissue followed by rapid expansion recovering the soft tissue envelope of the breast. This is of particular importance for nipple-sparing procedures. Recently, advances have been made in a hybrid approach that incorporates both prosthetic implants and autologous tissue in patients who desire autologous reconstruction but lack the soft-tissue volume required. These operations combine lipo-harvest fat for the uses of medium volume fat grafting to the breast in order to reconstruct the soft tissue envelope of the breast over an implant. These techniques are also powerful in targeted soft tissue reconstruction with flap.
The most popular autologous reconstructive options for flap reconstruction include the deep inferior epigastric perforator (DIEP) flap, transverse rectus abdominis myocutaneous (TRAM) flap, and the latissimus dorsi flap. Other autologous reconstructive options include the gluteal artery perforator flap and a novel approach utilizing a stacked perforator flaps from various donor sites.
Anatomy
Pertinent anatomy involved in breast reconstruction spans the entire thorax and abdomen. The breast is a mound of adipose, gland lobules, lactiferous ducts, and suspensory ligaments that sits atop the pectoralis major, serratus anterior, and intercostal muscles. Breast tissue extends from the second to sixth or seventh rib, bordered superiorly by the axillary tail and inferiorly by the inframammary fold. The female breast is enveloped by the superficial fascia of the anterior chest wall that is continuous with the neck superiorly and Camper’s abdominal fascia inferiorly. The base of the breast extends from the sternal border medially to the midaxillary line laterally ( Fig. 11.1 ).
At least 50% of the blood supply to the breast comes from the internal mammary artery, a branch of the subclavian artery. The remainder of the blood supply to the breast comes from branches of the lateral thoracic artery, axillary artery, and intercostal perforators, forming a well-collateralized anastomotic network. Venous return from the breast is primarily via the axillary vein, in addition to intercostal and internal mammary veins. Lymphatic drainage follows venous drainage.
The axilla is intimately connected with the breast, located between the upper extremity and thoracic wall. The lymph nodes in the axillary chain have important implications in breast cancer, as they receive about three quarters of all lymphatic drainage from the breast. The remaining one quarter of lymphatic drainage runs through lymph nodes in the internal mammary chain ( Fig. 11.2 ). Resection of lymph nodes during the treatment of breast cancer can result in secondary lymphedema due to interruption of the lymphatic network. This can cause swelling of the upper extremity, breast, or chest wall that may negatively impact patient quality of life.
The nerve supply to the breast was first described in 1840 by Sir Astley Cooper who identified the second to sixth intercostal nerves as its primary innervation along with intercommunicating mammary branches. Importantly, he described the innervation of the areola and nipple coming from mammary branches of the lateral cutaneous nerve at the T4 level, forming a plexus under the nipple. These branches provide sensation to the areola and nipple as well as motor supply to the smooth muscle of the nipple. For patients undergoing mastectomy these nerves cannot be spared, leaving the patient without sensation in the breast and nipple–areolar complex.
Of importance to note, the long thoracic nerve may be invaded by cancer or interrupted during breast surgery, which may lead to a presentation of winged scapula due to loss of function in the serratus anterior. However, preservation of the nerve during axillary nodal dissection and latissimus dorsi flap operations is of more clinical significance.
Abdominal anatomy has relevance in the topic of breast reconstruction, as the majority of autologous tissue used for breast reconstruction comes from the lower abdomen. These flaps typically include the skin and subcutaneous fat, with variations on inclusion of recuts abdominis fascia or muscle. The rectus abdominis is a vertically positioned abdominal muscle that originates on the pubis and inserts into cartilages of the fifth, sixth, and seventh ribs. The primary blood supply to the rectus abdominis includes the superior epigastric artery in the upper abdomen and the deep inferior epigastric artery in the lower abdomen. Of particular note for abdominal flaps, the deep inferior epigastric is the dominant blood supply, and the superior epigastric artery is typically variably collateralized in a zone above the umbilicus. The rectus abdominis receives its motor and sensory innervation primarily from the seventh to twelfth intercostal nerves. The nerves enter in variable segmental branches from lateral to medial; denervation of these nerves during abdominally based flaps results in a range of abdominal dysfunction secondary to segmental loss rectus motor function.
The posterior thorax is also relevant, as the latissimus dorsi may be used for breast reconstruction. The latissimus dorsi is a large, flat, triangular muscle that originates on the iliac crest, spinous processes of T7-L5, 10th–12th ribs, and inserts onto the bicipital groove of the humerus. The muscle gains its blood supply from dual vascular beds—one a dominant pedicle and the other segmental: the thoracodorsal artery, and from segmental paraspinal perforators and perforators of the lumbar artery. Venous drainage is achieved by the accompanying thoracodorsal veins and paraspinal venous perforators. The latissimus dorsi receives motor innervation by the thoracodorsal nerve, and sensory innervation from cutaneous branches of the intercostal nerves.
Preoperative Evaluation and Patient Assessment
Breast reconstruction is a complicated and elective part of breast cancer care. Primary reconstruction should be offered to all reasonable candidates, but not all patients are candidates for primary breast reconstruction. A thorough preoperative assessment of risk factors is critical. General preoperative risk factors for mortality include the presence of disseminated cancer, weight loss >10% in the last 6 months, age, WBC >11,000/mm 3 , and ASA classification and functional status. Risk factors specific to breast reconstruction are obesity, smoking, diabetes, abdominal scarring, lupus, and vasculitis. Patients undergoing surgery are strongly advised to stop smoking for at least 6–8 weeks before the procedures. Nicotine is a potent capillary level vasoconstrictor, and thus smokers are at a significantly elevated risk for mastectomy skin flap necrosis and may not be candidates for nipple-sparing procedures or even primary breast reconstruction. The surgeon can check carboxyhemoglobin levels prior to the operation in order to ensure that the patient was compliant with smoking cessation.
Radiation therapy in the setting of breast reconstruction is the most significant complicating factor. Previous radiation therapy is a relative contraindication for tissue expansion and implant-based breast reconstruction without the use of additional autologous tissue. Radiation-related fibrosis decreases skin compliance resulting in a high rate of device failure. The placement of a tissue expander in a previously radiated field may result in device exposure, failed expansion, inadequate expansion with lack of projection, poor wound healing, and an inability to achieve the desired result. Patients with implant-based breast reconstruction who receive postoperative radiation also face an increased risk of capsular contracture, with a reported incidence as high as 68%. A large cohort study in 2012 showed that, among patients who received breast reconstruction with tissue expanders/implants followed by radiation, the rate of reconstruction failure (defined by loss of reconstruction) at 3-year follow-up was 25.5%. This study showed that the remaining 75% of patients who did not experience failure were satisfied with their aesthetic outcome.
An alternative to tissue expander/implant reconstruction is autologous reconstruction. However, in general, patients at high risk for undergoing postmastectomy radiation should delay autologous breast reconstruction until after completion of radiation therapy. Radiation will significantly affect overlying skin. The internal mammary vessels are still suitable for microsurgical anastomosis. Therefore microsurgical free-tissue transfers may serve as a favorable option for this patient population. In the postradiated nonreconstructed chest wall mastectomy defect, the DIEP flap is the preferred reconstructive operation. These procedures are more technically challenging and require close monitoring during the acute postoperative period to ensure flap viability. Autologous tissue transfers also require adequate volume of soft tissue available for harvest. This may become an issue in thin patients with minimal abdominal soft tissue, patients with previous abdominoplasties, or in patients who desire breasts larger than what can be created with the available tissue. In these cases, surgeons can achieve the desired result by performing a hybrid implant/autologous reconstruction or other variation.
Procedures
In 2018 there was a total of 9497 DIEP flaps, 3799 TRAM flaps, and 4188 latissimus flaps performed. The DIEP and TRAM flaps are abdominal flaps based on the deep inferior epigastric artery and vein. The TRAM flap typically includes rectus abdominis muscle and fascia, while the DIEP flap spares the muscle and fascia ( Figs. 11.3 and 11.4 ). The DIEP flap is used as a free flap, meaning that the entire section of tissue and its blood supply are transplanted out of the abdomen on its vascular pedicle, shaped into a breast mound, and anastomosed to blood vessels in the chest ( Fig. 11.5 ). The internal mammary vessels are the most typical recipients of the free-flap anastomosis. The TRAM flap may be used as a free flap and may also be used as a rotational flap wherein the vascular pedicle remains intact as the flap is rotated superiorly into the breast pocket through a subcutaneous tunnel. Rotational TRAM flaps may also involve microsurgical anastomosis in the distal portion for additional venous outflow if the flap becomes congested. Free TRAM flaps may take small portions of muscle with minimal rectus dysfunction or may take all the rectus muscle. In TRAM flaps the rectus donor site requires repair. This is most frequently treated with the placement of prosthetic mesh, although biologic mesh/ADMs are rising in popularity.
Complications of the DIEP and TRAM flap include donor-site morbidity and flap morbidity. These include abdominal wound infection, bulge, hernia, partial flap necrosis, and total flap loss. New techniques are constantly being developed to address these issues. For example, in 2015 Rietjens et al. published their new technique for pedicled TRAM flap breast reconstruction, which achieved 0% abdominal hernia or bulge and 0% total flap loss at a median follow-up period of 13 months. Nonetheless, expected bulge rates in TRAM flaps run between 20% and 30% of cases while DIEP flaps and highly selective muscle-sparing free TRAMs report bulge rates of 12%–20% of cases. In addition, a larger number of these patients experience some degree of weakness, subclinical chronic bulges, and chronic pain. The donor-site effects must always be remembered in autologous breast reconstruction patients.
Risk factors play an important role in complication rates. A study by Chang et al. at the MD Anderson Cancer Center showed that obese and overweight patients had significantly higher rates of overall flap complications, total flap loss, and mastectomy flap necrosis when compared with normal-weight patients. Obese and overweight patients also had significantly higher rates of overall donor-site complications, infection, and hernia. A potential source of bias in this study is that the obese group had a significantly higher incidence of preoperative radiation and preoperative chemotherapy than the overweight or normal weight groups. Another study by Chang et al. showed that smokers undergoing free TRAM flap breast reconstruction experienced significantly higher rates of mastectomy flap necrosis (18.9% vs 9%, P =.005), donor-site complications (25.6% vs 14.2%, P =.007), abdominal flap necrosis (4.4% vs 0.8%, P =.025), and hernia (6.7% vs 2.1%, P =.016) when compared with nonsmokers.
Functional deficits may arise postoperatively; these vary primarily based on the amount of muscle removed and/or number of nerves either stretched or transected during flap harvest. Studies have shown that muscle-sparing techniques can significantly reduce donor-site morbidity and preserve abdominal wall function. Interestingly, it appears that patients with good preoperative abdominal muscle function may be better candidates for muscle-sparing procedures. DIEP flaps have the lowest published rates of abdominal dysfunction, most significantly in bilateral procedures. This outcome is in contrast to what may be seen with single or bilateral TRAM flaps that incorporate the entire rectus muscle. Petit et al. showed that 50% of patients who underwent a single-pedicle TRAM flap and 60% of patients who underwent a double-pedicle TRAM flap experienced functional impairment of the abdominal muscles. This study also showed that 30%–55% of patients undergoing single or bilateral TRAM flap breast reconstruction complained of back pain in the 6-month postoperative period. The degree of postoperative functional deficit is greater in patients receiving bilateral TRAM flaps compared with unilateral TRAM flaps. A study by Fitoussi et al. showed that, out of 12 patients receiving a double-pedicle TRAM flap breast reconstruction, none were able to sit up from a lying position without using their hands at an average of 28 months after the procedure. In contrast, 47% of patients receiving unilateral TRAM flaps were able to perform the task.
The latissimus dorsi flap is versatile flap with in general low donor-site morbidity. The latissimus dorsi is a reliable, large thin, well-vascularized flap with a broad scope of application ( Fig. 11.6 ). In the context of breast reconstruction, the latissimus flap comes with a caveat in that it most commonly requires tissue expansion and implant. It is thus a compromise flap, and not commonly utilized in primary breast reconstruction. In previously radiated patients who are not candidates for free-flap breast or for salvage of implant-based complications, the latissimus dorsi is an excellent option. It allows for replacement of lower pole breast skin and provides a large vascularized muscle for coverage of the implant. Prosthetic implants are typically required in conjunction with the latissimus flap to provide adequate volume and projection. Functional deficit associated with the latissimus flap is controversial, with older studies stating negligible deficit and newer studies revealing a high incidence of significant shoulder dysfunction. In patients receiving reconstruction with a latissimus flap, it is important to strengthen surrounding back and shoulder muscles to compensate for any potential loss of function. The most common complication of the latissimus flap is the formation of donor-site seroma. Drains may remain in the back for up to 6 weeks after the operation, and outpatient aspiration of a seroma may be necessary after removal of the drain. Fat necrosis or vascular compromise is rare with the latissimus flap, but donor-site marginal skin necrosis may be seen in smokers. Latissimus flaps may also be used in patients with multiple recurrent capsular contractures. These patients are treated with a complete capsulectomy. The pectoralis major in retropectoral reconstructions is placed back in anatomic position, with the implant now placed in the prepectoral and retrolatissimus position.
