Breast Cancer Surgery

Anatomy and Physiology

The breast lies on the anterior thoracic wall and is composed of skin, subcutaneous tissue, and breast tissue. Approximately two-thirds of breast tissue rests on the pectoralis major muscle, while the remaining one-third lies on the serratus anterior muscle as well as the upper portion of the oblique. There are two layers of fascia, including the superficial fascia, which is found deep to the dermis, as well as the deep fascia, which lies just anterior to the pectoralis major muscle fascia. This anatomy is important during a mastectomy as an essential principle of this technique involves removing the breast tissue with adhered pectoralis fascia to prove a complete resection. The anatomic boundaries of the breast are the second rib superiorly and the sixth rib inferiorly. The medial boundary is the lateral border of the sternum, and the lateral boundary is the midaxillary line. Often, the tissue of the breast can extend into the axilla; this is known as the axillary tail of Spence. 

The blood supply of the breast originates from three major arteries. The first arterial route accounts for approximately 60% of the breast’s blood supply. It originates from the anterior perforating intercostal arteries, which initially arise from the internal thoracic artery or internal mammary artery. These vessels are responsible for supplying the medial and central portions of the breast. An additional 30% of the blood supply to the breast originates from branches of the lateral thoracic artery, which is an extension of the axillary artery, as well as the pectoral branches of the thoracoacromial artery, which supply the upper outer quadrant. Lastly, the remainder of the breast receives its blood supply from branches of the posterior intercostal arteries. The subdermal plexus supplies the breast skin. Maintenance of the integrity of the internal thoracic artery is important for the nipple-areolar complex due to its perforating branches and anterior intercostal branches. Venous drainage of the breast follows the arterial supply. Drainage is towards the axilla and consists of three main veins. These include the perforating branches of the internal thoracic vein, the perforating branches of the posterior intercostal veins, as well as the tributaries of the axillary vein.

The major sensory innervation supplying the breast derives from the lateral and anterior cutaneous branches of the second through sixth intercostal nerves. An additional nerve to note is the intercostobrachial nerve, which originates as a lateral cutaneous branch of the second intercostal nerve. This nerve is responsible for supplying sensory innervation to the medial aspect of the upper arm, and surgeons generally encounter it during axillary dissection. Other nerves include the thoracodorsal nerve, which supplies the latissimus dorsi and can lead to “winged scapula” if inadvertently transected during surgery.[5]

In the breast, the majority of lymphatic drainage is through the axilla. The remainder of the breast (ie, medial aspect) drains via lymphatics traveling along the perforating branches of the internal mammary artery.  In breast surgery, there are 3levels of lymph nodes recognized, and these get labeled according to the relationship with the pectoralis minor. Level I lymph nodes are located lateral to the pectoralis minor. Level II lymph nodes are superficial and deep to the pectoralis minor.  Interpectoral, or Rotter’s nodes, are considered level II lymph nodes. Level III lymph nodes are present medial to the pectoralis minor.

Indications

Surgery has been the mainstay treatment of breast cancer for several decades.  Multiple trials in the last several decades have led to the evolution away from radical approaches towards less extreme, breast-conserving procedures.  Often, the surgical treatment of breast cancer is accompanied by adjuvant or neoadjuvant therapy, including hormonal therapy, chemotherapy, and/or radiation therapy.  

The NSABP B-06 randomized patients with stage I or II diseases with tumors less than 4 cm to mastectomy vs lumpectomy alone vs. lumpectomy with radiation. Overall survival showed no difference between the groups, but recurrence rates were significantly increased in lumpectomy-alone groups at 39.2% after 20 years. The standard of care has become lumpectomy with radiation in breast-conserving groups. Indications for breast-conserving surgery include DCIS/Tis and T1-2 tumors, if no contraindications to adjuvant radiation therapy, small tumors amenable to resection with clear margins, and acceptable cosmesis. Previous studies have cited a tumor size of 5 cm as a cutoff. However, treatment should be patient-specific, and women with larger breasts may still be eligible for breast-conserving surgery with a large tumor if the patient has sufficient breast size. Therefore, treatment decisions should vary on a case-by-case basis.[6]

Mastectomy, on the other hand, involves the complete removal of breast tissue.  Multiple indications for mastectomy exist. These include patients with advanced disease, including T2 (greater than 5 cm) tumors, multicentric or multifocal disease, chest wall involvement, or inflammatory breast cancer, which is generally considered T4 disease. Another indication for mastectomy includes patients with Paget disease, indicating tumor cells of the epidermis of the nipple-areolar complex. Up to 90% of patients with Paget disease have associated cancer in another area of the unilateral breast. In patients without additional cancer elsewhere in the breast, central lumpectomy with sentinel lymph node biopsy is a viable option if followed by whole breast radiation treatment. Mastectomy is also the indicated approach in patients who initially undergo breast-conserving surgery and have persistently positive margins, as well as patients who previously underwent breast-conserving surgery and radiation and develop a recurrence or new primary cancer in the unilateral breast.  

Prophylactic mastectomies have increased in the past several years; this is partially due to a gross misunderstanding of the overall likelihood of developing contralateral breast cancer. Contralateral prophylactic mastectomy is generally most recommended in patients who have an increased lifetime risk of developing contralateral breast cancer. This situation includes patients who are BRCA positive, have a strong family history, or any young patient with biologically aggressive breast disease.[7] Some patients elect to have skin-sparing mastectomies, particularly if electing for reconstructive options. Patients who are eligible for skin-sparing mastectomies include those in which adequate margins are achievable with this approach.

In the discussion of the surgical treatment of breast cancer, the management of the axilla is an integral component with constantly evolving recommendations. Of note, excision of lymph nodes only provides staging and prognostic value, rather than treatment. Overall, recommendations have changed toward doing less over time, and several landmark studies have paved the path toward current axillary management.  The overall goal has been determining how to avoid overtreatment of the axilla, thus minimizing associated complications of axillary dissection, including lymphedema. The NSABP B-32 trial, for example, examined patients who received axillary lymph node dissection only in the setting of positive sentinel lymph nodes.  This approach remained the standard of care for over a decade. Multiple studies, including the NSABP B-32 trial, however, demonstrated that many women with one positive sentinel lymph node did not have further positive lymph nodes upon completion of dissection.[8] The American College of Surgeons Oncology Group trial Z0011 was a landmark study that provided guidelines for the axillary management of early-stage breast cancer.  In summary, the trial recommended that in patients with tumors less than 5 cm in size, with clinically lymph-node negative axilla, less than 3 positive lymph nodes, and treatment with breast-conserving therapy (to include whole breast radiation) and adjuvant systemic hormonal therapy or chemotherapy, completion axillary lymph node dissection can be safely omitted. Sentinel lymph node biopsy is indicated in any patient with invasive breast cancer and clinically negative axilla. Also, sentinel lymph node biopsy is the recommendation in patients undergoing mastectomy for any high-risk lesions, including DCIS.[9]

On the other hand, a complete axillary dissection is necessary in certain circumstances. It is recommended at the time of the primary procedure in patients who have locally advanced (clinical stage T4) or inflammatory breast cancer, high-risk T3 breast cancer, occult cancer with proven metastasis in the axilla, positive sentinel lymph nodes that are outside the Z0011 selection criteria (ie, more than 2 lymph nodes are positive, matted nodes, mastectomy, breast conservation therapy without whole-breast radiation therapy), failed sentinel lymph node mapping, axillary recurrence following previous treatment for breast cancer, and in those with persistently positive sentinel lymph nodes following neoadjuvant chemotherapy. Additionally, it is a requirement in any clinically node-positive patients. In other words, these patients have biopsy-proven metastasis in an axillary lymph node, and no neoadjuvant chemotherapy is planned.[9]

Contraindications

Absolute contraindications to lumpectomy include prior radiation therapy, pregnancy, multicentric tumor (tumors in more than one quadrant of the breast), inability to obtain clear margins (large tumor or invasion into adjacent structures), and physical inability to tolerate radiation therapy. Relative contraindications include multifocal tumors, connective tissue disease, and a large tumor-to-breast size ratio. Recurrences or breast cancer in a breast previously treated with radiation require management with mastectomy.[6] There are few contraindications to mastectomy. Mastectomy is contraindicated in patients with known metastatic disease, individuals with a poor performance status who are unable to tolerate general anesthesia, as well as in certain patients with advanced locoregional disease who require neoadjuvant treatment to downstage their tumor prior to any surgical resection.

Equipment

An essential component of the surgical treatment of breast cancer, if performing breast conservation surgery, relies on precise localization. The surgical oncologist must work closely with radiologists for the best possible outcomes. There are multiple preoperative localization options available. The most widely known localization technique involves wire needle localization. Wires often get placed using mammography or ultrasound guidance, with placement on the same day of breast surgery. Multiple wires are occasionally required to bracket tumors greater than or equal to 2 cm. There are various disadvantages to wire localization, including scheduling issues due to the availability of oncologic surgeons and radiology schedules. Additionally, the wire can migrate, and cause pneumothorax or hemothorax, hematoma, or breast implant puncture. Retained wire fragments can occur if the wire is inadvertently cut during the procedure.[10]

Recent developments in localization devices do not require the use of a wire; this avoids the risk of the wire becoming dislodged or migrating to another location. Some other advantages include increased flexibility in timing, reduced length of stay on the day of surgery, and localization access independent of the surgical approach. Non-wire devices can be placed anywhere between five and thirty days before the procedure, which provides a distinct advantage in the uncoupling of schedule coordination between involved personnel. 

Non-wire devices are further categorized into radioactive and non-radioactive devices. Radioactive seed localization (RSL) consists of a 5-mm I125 pellet with a titanium shell. Deployment is comparable to biopsy clip placement.  Placement can be up to 5 days before surgery, but sometimes placement is on the same day of surgery. The seed requires the use of an intraoperative gamma probe to locate and remove the target lesion properly. Because RSL has been proven to be safe, and effective, and possibly reduce the rate of positive margins, it is quickly becoming a popular option among surgeons across the nation.

Non-radioactive devices include the SCOUT RADAR device, MAGSEED, and RFIL. One additional advantage of non-radioactive non-wire devices compared to radioactive ones is that the lack of radioactivity allows for deployment in a separate facility if needed. These devices often get placed up to thirty days before surgery. The oncologic surgeon then utilizes a special intraoperative probe that emits infrared light to locate and remove the target lesion.[11]

Personnel

The surgical treatment of breast cancer requires the contribution of a comprehensive interprofessional care team.  A radiologist must be available in coordination with the surgeon’s schedule to verify the specimen contains any biopsy clip, seed, or complete intact wire.  This approach ensures the removal of the target lesion before the completion of surgery. Some surgeons also elect to have pathology verify margins intra-operatively.  

Preparation

Typically, a patient with an abnormal finding noted on clinical exam and/or imaging will first undergo a core needle biopsy for diagnostic purposes.  At the time of biopsy, a clip will also be placed to guide future surgical management. This marker is particularly helpful in patients who undergo neoadjuvant chemotherapy, as these lesions may often become difficult to locate. After the biopsy, patients may or may not undergo additional testing, including axillary ultrasound, staging computed tomography of chest, abdomen, and pelvis, breast magnetic resonance image, complete blood count, comprehensive metabolic panel, and/or fludeoxyglucose positron emission tomography/computed tomography. This is generally a consideration with additional signs or symptoms. Additionally, based on the stage of cancer, the patient may or may not meet with radiation oncology, medical oncology, genetics, and/or plastic surgery. They also may require discussion at a tumor board.  

Technique or Treatment

Lumpectomy

There are various terms used to describe breast-conserving surgery, including quadrantectomy, lumpectomy, or partial mastectomy.  These terms may vary slightly in technique but retain the goal of breast preservation. Non-palpable tumors require the aid of image-guided localization techniques, as described in the above equipment section. Quadrantectomy involves excision of the tumor, including a 2- to 3-m margin, pectoralis fascia, as well as the overlying skin. On the other hand, lumpectomy indicates a less generous tissue excision with a 1 cm margin. The majority of early-stage tumors do not necessitate a quadrantectomy and thus will not be further described in detail.

The incision choice for a lumpectomy is based on numerous factors.  It may be located within the Langer lines over the mass, whenever technically or cosmetically feasible, or a radial incision, particularly in the case of a large tumor.  Regardless of the incision location, it is crucial to keep in mind the possibility of a future mastectomy. Following the incision, subcutaneous flaps are formed surrounding the tumor. Once removed, it is vital to orient the specimen, particularly if the need for re-excision arises in the future. Intraoperative specimen imaging is then performed to verify the presence of the biopsy clip and any preoperatively placed markers. If a close margin is suspected or indicated, many surgeons will excise an additional 0.5 to 1.0 cm of tissue to accompany the specimen. “Shave margins,” or excising an additional 1 mm of tissue, have been shown to reduce margin positivity and re-excision rates possibly. It is also common practice to place radiopaque clips in the tumor cavity to guide future radiation treatment as well as follow-up imaging. The surgeon then closes the incision in layers. Generally, an absorbable suture is used on the skin.[12]

Mastectomy

Mastectomy techniques have drastically transformed since the historic radical mastectomy described by William Halsted in the 1890s, which involved en bloc resection of the entire breast, pectoralis major, and lymphadenectomy. This approach correlated with high morbidity and significant cosmetic deformities. In 1972, the modified radical mastectomy was described by John Madden, and this technique remains employed in modern medicine. This procedure involved an elliptical incision, including the nipple-areolar complex, and removal of all breast tissue as well as pectoralis major fascia. A modified radical mastectomy also involves the excision of level I-III axillary lymph nodes. A simple mastectomy, on the other hand, removes all breast tissue without necessitating a complete axillary node dissection.

Mastectomy generally involves an elliptical incision and raising uniform flaps.  These flaps vary typically in thickness but usually range between 5 mm and 1.0 cm.  Ideally, all breast tissue gets excised while preserving blood supply to the overlying skin.  These flaps extend to the clavicle superiorly, the lateral edge of the sternum medially, the inframammary fold inferiorly, and the anterior edge of the latissimus dorsi laterally. Two additional forms of mastectomy also exist. These include skin-sparing and nipple-sparing mastectomies. These procedures are performed with immediate reconstruction. It is important to remember to send a frozen section of the nipple-areolar complex on the ipsilateral side of the tumor to ensure it is uninvolved and, therefore, may be spared in the resection.[13]

Sentinel Node Biopsy

The sentinel lymph node biopsy is an essential component of staging in patients with early-stage breast cancer who are clinically node-negative.  In both sentinel and axillary lymph node dissection, short-acting neuromuscular blocking agents are preferred during induction so that patients are not paralyzed, which allows for proper identification of the thoracodorsal, long thoracic, and medial and lateral pectoral nerves to help avoid inadvertent injury. Generally, for the identification of nodes, most surgeons prefer a dual tracer technique, as this has the highest sensitivity.  First, a technetium-99m sulfur colloid is used as a radioactive tracer and is injected intradermally into the site of the tumor or the areolar subdermal plexus. Next, the surgeon may inject isosulfan blue or diluted methylene blue dye to aid in identifying the sentinel lymph nodes. This dye is also typically injected into the subdermal plexus of the areola.  A gamma probe is then used to determine the location of the probable sentinel node. A small incision is made followed by dissection down to the clavipectoral fascia. The gamma probe is then used to locate the hottest node. This node is excised. Next, the gamma probe helps to identify any additional sentinel nodes, which are removed if greater than 10% of counts of the sentinel node, blue in color, or suspicious. These nodes are carefully removed and sent for either a frozen section or a permanent section, depending on the surgeon's preference.[14]

Axillary Node Dissection

It is currently standard of care to perform axillary node dissection on a select group of patients, as indicated above. First, the surgeon palpates the pectoralis major and forms a “lazy S” incision using a scalpel. Next, electrocautery is used to both dissect through the subcutaneous tissue as well as raise skin flaps. The inferior skin flap should be raised to the level of the 5th rib. The borders of the axilla include the axillary vein, the pectoralis major and minor as well as the latissimus dorsi muscle. The lateral border of the pectoralis major gets elevated to expose the interpectoral (Rotter’s) nodes, which are dissected off the pectoralis minor muscle. Next, the axillary fascia gets divided to free up the lateral edge of the pectoralis minor. This step will expose the nodal tissue to be excised with the specimen. In bulky disease, the pectoralis minor muscle may require division to improve the exposure of the upper axillary lymph nodes. The wound should be irrigated, and hemostasis assured. A single drain should be placed and lie inferior to the axillary vein. The incision is typically closed using deep dermal 3-0 absorbable sutures followed by skin adhesive or absorbable sutures.[15]

Complications

Generally speaking, surgery for breast cancer is a low-risk procedure.  However, a multitude of complications can occur for both lumpectomy and/or mastectomy. In a lumpectomy, positive margins requiring re-excision or mastectomy may occur. Additionally, both procedures may lead to a seroma, hematoma, infection, or skin necrosis. Injury to surrounding blood vessels, including the axillary vein, may occur. Nerve injury or transection may also occur, leading to sensory or motor defects. An additional complication includes lymphedema, which may occur particularly in the setting of complete axillary node dissection.

Clinical Significance

Breast cancer often requires surgery as part of curative treatment. The decision to proceed with mastectomy or breast conservation surgery remains both patient- and disease-driven. Some patients require upfront chemotherapy and/or radiation treatment to downstage their tumor or axillary nodes, as is the case in inflammatory breast cancer. In most early-stage breast cancer, surgery is the first step in treatment. Following surgery, adjuvant radiation is recommended in nearly all patients who undergo breast conservation therapy as recurrence rates are unacceptably high without it. Endocrine therapy is recommended for at least five years in those whose tumors are positive for hormone receptors (ie, estrogen, progesterone) and is often recommended for women considered high risk as prophylactic therapy. Chemotherapy is also recommended in more aggressive tumors as well as those that have a negative expression of estrogen, progesterone, and HER2neu receptors. Surveillance guidelines following cure involve at least annual mammography to assess for local recurrence or contralateral breast cancers. The timing of initiation is generally six months after radiation therapy is completed. If the patient is receiving semiannual screening, current guidelines recommend returning to annual surveillance after 2 years.[16]

Enhancing Healthcare Team Outcomes

Breast cancer involves an interprofessional team to achieve the best possible outcomes. This team includes oncologic and plastic surgeons, medical oncology, radiation oncology, pathology, radiology, nurse navigators, and multiple other individuals to discuss each patient and formulate a treatment plan. Oncology specialty nursing staff will assist during procedures, provide post-procedural follow-up care, and administer medication, and answer patient questions. These nurses must keep the clinician staff up to speed on all developments for the patient's progress or lack thereof. In cases where chemotherapy will be an adjunct, a board-certified oncology pharmacist should work with the oncology team to select the appropriate agents, verify dosing, and counsel the patient on adverse effects, also reporting any concerns to the team. The outcomes for patients with breast cancer continue to improve with the increased use of interprofessional teams, as demonstrated in multiple retrospective studies.

Nursing, Allied Health, and Interprofessional Team Interventions

Nurses are especially crucial in the care of patients with breast cancer undergoing surgery. Many cancer care centers employ nurse navigators or specialized oncology nurses who can guide patients through each step of treatment and answer any questions that the patient or family may have.  Additionally, nurses are especially crucial in patients who have drains placed, as proper drain care is essential to prevent infection and other complications from occurring. This care involves teaching the patient about their drains so they can properly care for themselves after discharge. Most patients do not require much pain medication following breast cancer surgery. However, if discharged with medication, especially opioids, the nurse needs to review these medications with the patient for safety purposes.  

Nursing, Allied Health, and Interprofessional Team Monitoring

Nurses must be aware of the potential complications of these procedures to properly monitor patients in the postoperative period.  In particular, monitoring the incision for any hematoma or seroma formation to let the surgeon know of any complications that may occur. Also, if drains are present, monitoring the quality and quantity of output is essential.