Technique of axillary lymph node dissection

INTRODUCTION — Evaluation of the axilla provides information for treatment decisions in patients with invasive breast cancer. Axillary lymph node dissection (ALND) is the standard initial approach for breast cancer patients who are clinically node positive. Sentinel node biopsy is the standard initial approach for patients with early-stage breast cancer who are clinically node negative.

The technique of ALND will be reviewed here. The approach to management of the regional lymph nodes in breast cancer, sentinel node biopsy indications and outcomes, sentinel node biopsy techniques, and effect of ALND on patient survival are discussed elsewhere. (See "Overview of management of the regional lymph nodes in breast cancer" and "Overview of sentinel lymph node biopsy in breast cancer" and "Sentinel lymph node biopsy in breast cancer: Techniques".)

INDICATIONS

An axillary lymph node dissection (ALND) is performed with the primary breast procedure (eg, lumpectomy or mastectomy) in patients who have:

●Locally advanced (T3-T4; N0-2) or inflammatory breast cancer. (See "Overview of sentinel lymph node biopsy in breast cancer", section on 'Contraindications'.)

●Needle-biopsy-proven metastatic disease in axillary lymph node(s), which are either clinically palpable or nonpalpable but abnormal by imaging (mostly ultrasound) criteria. (See "Overview of sentinel lymph node biopsy in breast cancer", section on 'Preoperative axilla evaluation'.)

Even if neoadjuvant chemotherapy is administered to these patients, ALND should still be performed, regardless of the patient's response. (See "Overview of sentinel lymph node biopsy in breast cancer", section on 'Neoadjuvant chemotherapy'.)

For all other patients who are diagnosed with breast cancer, a sentinel lymph node biopsy (SLNB) is performed in lieu of ALND before or with the primary breast procedure (eg, lumpectomy or mastectomy). (See "Overview of sentinel lymph node biopsy in breast cancer".)

Following SLNB, a completion ALND (cALND) is performed for:

●Three or more positive lymph nodes found in patients with small (≤5 cm) tumors (T1 or T2). (See "Overview of sentinel lymph node biopsy in breast cancer", section on 'Three or more sentinel node metastases'.)

●Any number of positive lymph node(s) found in patients with large (>5 cm) tumors (T3). (See "Overview of sentinel lymph node biopsy in breast cancer", section on 'Sentinel node metastasis with large tumor'.)

●Any number of positive lymph node(s) found with extranodal extension (ENE) of tumor cells. (See "Overview of sentinel lymph node biopsy in breast cancer", section on 'Sentinel node metastasis with extranodal extension'.)

●Any number of positive lymph node(s) found in patients who will not receive whole breast irradiation because they undergo a mastectomy, receive partial breast irradiation, or refuse breast irradiation.

SURGICAL ANATOMY — The surgeon must understand the complex anatomy of the axilla in order to preserve maximum muscular function and sensation (figure 1 and figure 2) [1-3].

Borders of the axilla — The boundaries of the axillary lymph node dissection (ALND) are the axillary vein superiorly, the serratus anterior muscle medially, and the latissimus dorsi muscle laterally (figure 3). From the anatomic perspective, the axillary space is actually a pyramidal compartment with an apex, base, and four walls.

●The apex of the axilla is the costoclavicular ligament.

●The base of the axilla is comprised of skin and axillary fascia.

●The anterior boundary of the axilla is the pectoralis major and pectoralis minor and subclavius muscles, enclosed in the clavipectoral fascia.

●The posterior boundary of the axilla is the subscapularis, teres minor, and latissimus dorsi muscles.

●The lateral wall of the axilla is the narrow space at the bicipital groove on the humerus between the insertions of the muscles of the anterior and posterior walls.

●The medial border of the axilla is the ribs and intercostal muscles covered with the serratus anterior muscle.

Contents of the axilla — The axilla contains the blood vessels, lymphatic trunks, and nerves to the arm. The dissection should be inferior to the axillary vein; thus, the axillary artery and brachial plexus (figure 4) are superior to the surgical field.

Motor nerves — The major motor nerves of the axilla encountered during axillary dissection include:

●The long thoracic nerve ("nerve of Bell") runs parallel to the chest wall and innervates the serratus anterior muscle. If this nerve is injured, the patient will have a protruding "winged" scapula deformity.

●The thoracodorsal nerve marks the deep aspect of the axillary space and innervates the latissimus dorsi muscle. Injury to this nerve partially denervates the latissimus dorsi and may lead to mild weakness of internal rotation and shoulder adduction. Usually, the deficit is well compensated by the remaining intact shoulder musculature.

●The medial and lateral pectoral nerves innervate the pectoralis minor and major muscles. Injury to these nerves leads to denervation atrophy and shortening of the pectoral muscles with limitation of shoulder mobility and compromise of the cosmetic result.

Sensory nerves — The intercostobrachial nerves are sensory nerves that traverse the axilla to supply the skin on the medial and posterior arm, axilla, and posterior axillary line. The intercostobrachial nerves exit the fascia of the chest wall at the second and third intercostal spaces. The highest intercostal brachial nerves supply sensation to the upper medial arm, and the patient will have diminished sensation or hyperesthesias if these nerves are injured. The lower intercostal nerves supply skin sensation to the axilla and are rarely saved since they course through the specimen.

Lymph nodes — The axillary lymph nodes are divided into three levels based upon their relationship to the pectoralis minor muscle (figure 5):

●Level I: Inferior and lateral to the pectoralis minor muscle.

●Level II: Posterior to the pectoralis minor and below the axillary vein.

●Level III (infraclavicular): Medial to the pectoralis minor and against the chest wall; involvement of these nodes alters nodal staging classification due to their poor prognostic significance. Level III lymph node involvement automatically confers a pN3 status (table 1) [4]. (See "Tumor, node, metastasis (TNM) staging classification for breast cancer".)

Blood vessels — The axillary artery and vein are enclosed within the axillary sheath with the brachial plexus (figure 6). The thoracodorsal artery and vein travel with the thoracodorsal nerve and should be preserved (figure 7).

PREOPERATIVE PREPARATION

●Operating room safety – Operating room safety, including obtaining informed consent and site marking, is reviewed elsewhere. (See "Patient safety in the operating room".)

●Anesthesia – An axillary lymph node dissection (ALND) is performed under general anesthesia. The patient should not be paralyzed, so that testing of the large motor nerves during dissection is possible.

●Antibiotics – A preoperative antibiotic, such as cefazolin, should be administered after arriving in the operating room and before the incision is made [5-7]. The efficacy of antibiotic prophylaxis decreases if administered more than one hour before surgery (table 2) [8-10].

A meta-analysis of the randomized controlled trials of preoperative antibiotics versus placebo in patients undergoing breast surgery found that the use of preoperative antibiotics was associated with a significant reduction in infection (relative risk 0.60; 95% CI 0.45-0.81) [11]. (See "Antimicrobial prophylaxis for prevention of surgical site infection in adults".)

●Deep venous thrombosis prophylaxis – For patients undergoing general anesthesia, primary prophylaxis for prevention of deep venous thrombosis, such as sequential compression devices, should be employed. (See "Prevention of venous thromboembolic disease in adult nonorthopedic surgical patients".)

SURGICAL TECHNIQUE — An axillary lymph node dissection (ALND) is usually performed through a small incision, and confirmation of the anatomic landmarks is crucial for avoiding injuries with functional consequences [1-3]. (See 'Surgical anatomy' above.)

Positioning — Patient positioning should allow maximum exposure of the axilla. The patient is positioned supine with their arms extended on arm boards at ≤90 degrees abduction from the chest wall. Arm positioning with >90 degrees of abduction from the chest wall increases the potential for stretching the brachial plexus and should be avoided. It is important to position the arm while the patient is awake to make sure the arm is not abducted beyond what is comfortable for the patient, especially if there are preexisting problems with shoulder mobility.

The ipsilateral arm can be included in the prepped field at the discretion of the surgeon, allowing the arm to be mobilized during the procedure. The lateral chest wall should be positioned along the edge of the operating table. After the patient is securely belted, the table can be tilted with the operative side up to allow optimal visualization of the axilla.

Incision — An ALND may be performed within the context of a modified radical mastectomy for patients requiring complete removal of the breast, in combination with a partial mastectomy for breast conservation, or as a separate procedure. (See "Breast-conserving therapy" and "Mastectomy".)

The incision will vary depending upon the breast surgery being performed:

●For patients undergoing an ALND alone or concurrently with partial mastectomy, a curvilinear incision is made approximately 1 to 2 cm below the edge of the axillary hair line following the natural skin folds (Langer's lines), extending from the anterior to the posterior axillary fold (figure 8). A better cosmetic result is obtained if the incision does not cross the anterior or posterior axillary folds.

●For patients undergoing standard modified radical mastectomy without reconstruction, the ALND can be performed through the mastectomy incision once the breast has been removed.

●For patients undergoing a skin-sparing modified radical mastectomy with immediate reconstruction, the skin opening can be positioned over the axilla once the breast is removed to allow for the ALND. A small radial skin incision can be extended laterally to facilitate this approach. Alternatively, a separate incision in the axilla can be used when it is not feasible to reach the axilla through the breast skin opening.

Critical steps of the dissection

●Definition of pectoralis muscles – The lateral edge of the pectoralis major muscle is retracted medially to expose the pectoralis minor muscle and allow interpectoral dissection of Rotter's lymph nodes. The medial pectoral neurovascular bundle, which innervates the pectoralis major and minor muscles, should be preserved during the dissection. The neurovascular bundle passes through the pectoralis minor muscle in 60 percent of patients and passes laterally around the pectoralis minor muscle in 40 percent.

●Identification of latissimus dorsi – The anterior surface of the latissimus dorsi muscle is the lateral border of the axillary dissection (figure 9). Dissection along the latissimus dorsi border is extended inferiorly until the muscle begins to pull toward the chest wall and superiorly to the tendon of insertion.

●Clavipectoral fascia – The clavipectoral fascia is divided at the level of the inferior axillary sheath to expose the underlying fat pad and axillary lymph nodes within the fat.

●Axillary vein – Dissection is carried posteriorly until the axillary vein is visualized, with care not to open the axillary sheath and strip or skeletonize the vein unless there is extensive nodal disease, because this increases the risk of injury to the vessels and lymphatics, which can increase the risk of lymphedema [2]. The axillary vein often bifurcates or trifurcates within the axillary space. Thus, transverse venous structures high in the axilla should never be ligated, even when they appear smaller than that expected for an axillary vein.

●Mobilization of the axillary fat pad – The fatty tissue and nodes are dissected off the chest wall and the inferior surface of the axillary vein.

●Identification of intercostobrachial nerves – The sensory intercostobrachial nerves are encountered during the lateral dissection along the latissimus dorsi. It is difficult to spare branches that are located far inferior to the axillary vein, but this can be accomplished with careful dissection. By sharp dissection, the adventitial tissues can be incised along the nerve so that the nerve can be retracted anteriorly away from the underlying axillary fat pad and contents. If the intercostobrachial nerve branches cannot be spared, ligation should be performed sharply to avoid electrocautery conduction injury.

●Identification of motor nerves – The positions of the long thoracic nerve and thoracodorsal neurovascular bundle can vary slightly from patient to patient. The best approach is to preserve all neural and vascular structures in unexpected positions, until the full axillary anatomy can be determined and before anything critical is sacrificed.

The long thoracic nerve is identified by blunt dissection just below the medial aspect of the axillary vein and just lateral to the chest wall. One can often feel the nerve prior to visualizing it by palpating the tissues along the chest wall (figure 10). Once the nerve is identified, the plane is extended inferiorly for the length of the axillary field. It is important to try to keep the long thoracic nerve against the chest wall to reduce the likelihood of injury. The fascial layer on the serratus anterior that holds the long thoracic nerve in place should not be breached, to avoid injury to the nerve.

The thoracodorsal neurovascular bundle can be identified by dissecting in the mid-axilla just inferior to the axillary vein (figure 7). There is often a large superficial venous tributary arising from the axillary vein, called the thoracoepigastric vein, which is often just anterior to the position of the thoracodorsal neurovascular bundle. This superficial vein should not be transected until the neurovascular bundle is confirmed.

●Extent of dissection – The extent of dissection is defined by anatomic location (figure 11). An accurate determination of the nodal level of a resected specimen can only be made if the specimen is marked by the surgeon or separated into levels before it is evaluated by the pathologist. (See 'Surgical anatomy' above.)

The extent of dissection is a tradeoff between the greater morbidity of a more extensive ALND and the possibility of leaving residual untreated axillary disease. In general, a level I and II anatomic ALND is the preferred procedure for axillary assessment [12]. The typical level I/II dissection should yield ≥10 axillary lymph nodes, although the range is highly variable. The risk of axillary recurrence is inversely related to the number of removed axillary lymph nodes in a formal ALND. The axillary failure rates increase when fewer than five lymph nodes (LNs) are removed (5 to 21 percent) as compared with when more than five LNs are removed (3 to 5 percent) [13-15]. (See 'Lymph nodes' above.)

Routine removal of level III nodes is unnecessary for staging but should be carried out to maximize local control if grossly positive axillary lymph nodes are identified intraoperatively. Level III lymph node dissection significantly increases the morbidity of the ALND. This level is not generally formally dissected; clinically suspicious level III nodes are separately resected and labeled as such for the pathologist. The reported incidence of skip metastases in the level III nodes with uninvolved level I nodes ranges from 0.2 to 3.1 percent [16-21]. These numbers correlate well with locoregional recurrence rates following a level I and II ALND in women undergoing breast-conserving surgery (3 percent or less) [13,22-24]. (See "Breast-conserving therapy".)

●Completion of dissection – Once the long thoracic and thoracodorsal nerves have been identified, the axillary contents can be removed from the defined boundaries. Blunt dissection is used to define the tissue planes between the axillary fat pad and contents and the underlying structures, progressing from superior to inferior in the operative field (figure 12). Palpation of level III nodes can then be performed by running the ventral surface of the index finger behind the pectoralis minor muscle and toward the infraclavicular space. If clinically suspicious nodes are palpated, they can be separately resected by retracting the pectoralis minor muscle for exposure.

Drains — Before closure, some surgeons place a closed suction drain in the axillary space through a separate stab wound in the low axilla above the bra line. Other surgeons prefer not to place a drain; they aspirate any seroma that develops in the postoperative period, which is more comfortable for the patient and allows discharge after surgery without a hospital stay or cumbersome drain care [25]. Meta-analyses of available randomized trials have demonstrated that axillary drains decrease seroma formation and the volume and frequency of postoperative seroma aspiration; however, they extend hospital stay and do not affect the incidence of wound infection [26-28].

Axillary reverse mapping — Axillary reverse mapping (ARM) is an experimental technique being investigated as a method of preserving the upper extremity lymphatics during ALND in an attempt to reduce the risk of postoperative lymphedema [29-31]. Blue dye is injected in the upper inner ipsilateral arm, and blue lymphatics and nodes are avoided during ALND. In two studies of 23 patients each, metastases were present in the nodes related to ARM sampling in 14 and 60 percent of patients, respectively [29,31,32]. Thus, further studies are needed to determine the long-term oncologic outcomes of this novel technique, which should not be used outside of a clinical trial.

POSTOPERATIVE CARE — Pain control is achieved with acetaminophen or a short course of narcotics. (See "Approach to the management of acute pain in adults".)

If a drain was used, the patient is instructed on the care of the axillary drain and asked to keep a daily log of the drainage volume. The drain can be removed when the output is 30 mL or less a day. Activity restrictions include avoidance of submersion of the incision in water and avoidance of driving, strenuous activity, or heavy lifting while the drain is in place. After drain removal, patients are encouraged to gradually increase their level of activity and range of motion.

If a drain was not used, the patient should be evaluated for seroma formation a week after surgery. If the seroma is large or symptomatic, it should be aspirated. A small seroma will usually respond to conservative care with rest, arm elevation, and icing of the axilla.

Simple range-of-motion exercises will enable most patients to resume full activity. Some patients may require physical therapy to regain full range of motion. Patients should receive instruction in the prevention and recognition of lymphedema. (See "Clinical staging and conservative management of peripheral lymphedema" and "Patient education: Lymphedema after cancer surgery (Beyond the Basics)".)

COMPLICATIONS — The anatomic disruption caused by axillary lymph node dissection (ALND) may result in lymphedema, nerve injury, and shoulder dysfunction, which compromise functionality and quality of life.

●Infection – The incidence of postoperative wound infection following axillary dissection varies from 3 to 15 percent in the literature, though it is difficult to assess the contribution of ALND in the setting of a combined breast surgical procedure [33-36]. The most common organisms are usually gram positive (streptococcal or staphylococcal species) and will respond to treatment with appropriate oral antibiotics. If there is an underlying seroma, it should be aspirated and cultured to direct antibiotic treatment.

●Hematoma – The reported incidence of postoperative hematoma has varied from 2 to 10 percent [33,34,37].

●Seroma – The normal lymphatic drainage of the breast to the axilla can lead to seroma formation after axillary dissection [37]. Seromas can be diminished with the use of drains or managed via percutaneous aspiration [38]. (See 'Drains' above.)

●Arm morbidity – Lymphedema of the arm is a potential and serious complication of ALND. The rate varies substantially with the level of dissection and whether postoperative radiation therapy is used.

In a meta-analysis of 98 prospective or retrospective cohort studies and randomized control trials that included patients undergoing an axillary procedure for breast cancer, patients undergoing a radical mastectomy were significantly more likely to develop arm lymphedema compared with patients undergoing a less aggressive mastectomy procedure (risk ratio [RR] 3.28, 95% CI 2.35-4.59) [39]. Additional pertinent risks for lymphedema included:

•Patients undergoing a mastectomy were significantly more likely to develop arm lymphedema compared with patients undergoing a partial mastectomy (RR 1.42, 95% CI 1.15-1.76).

•Patients undergoing an axillary lymph node dissection were significantly more likely to develop lymphedema compared with patients undergoing a sentinel lymph node dissection (RR 3.07, 95% CI 2.20-4.29).

•Patients undergoing any radiation treatments to the axilla had a higher rate of lymphedema compared with no axillary radiation treatments (RR 2.97, 95% CI 2.06-4.28).

•Patients with positive axillary lymph nodes also had a higher rate of lymphedema compared with patients who were axillary node negative (RR 1.54, 95% CI 1.32-1.80).

•Shoulder stiffness and numbness and paresthesias in the upper arm are common complaints following an ALND. Although these symptoms do not usually interfere with daily living, they may reduce the quality of life [40-44]. In one series, 42 percent of women had subjective or objective arm impairment (eg, pain, reduced grip strength) one year after an ALND [43].

Prevention, clinical manifestations and diagnosis, and management of lymphedema are discussed separately. (See "Clinical features and diagnosis of peripheral lymphedema" and "Clinical staging and conservative management of peripheral lymphedema" and "Patient education: Lymphedema after cancer surgery (Beyond the Basics)".)

●Nerve injury – The risk of major motor nerve injury following an ALND is <1 percent. Injury to the long thoracic nerve results in a winged scapula. Injury to the thoracodorsal nerve weakens shoulder adduction and internal rotation. Injury to the medial pectoral nerve may lead to atrophy of the lateral aspect of the pectoralis major muscle, which may impact the overall cosmetic result. Transection of the intercostobrachial nerve results in numbness and paresthesias on the inner upper arm. (See 'Motor nerves' above and "Physical rehabilitation for cancer survivors".)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Breast surgery".)

SUMMARY AND RECOMMENDATIONS

●Indications – Evaluation of the axilla provides information for treatment decisions in patients with invasive breast cancer. Axillary lymph node dissection (ALND) remains the standard initial approach for breast cancer patients who have locally advanced or inflammatory breast cancer and needle-biopsy-proven metastatic disease in axillary lymph node(s). Sentinel lymph node biopsy (SLNB) is the standard initial approach for all other patients with early-stage breast cancer who are clinically node negative. (See 'Indications' above.)

Following SLNB, a completion ALND (cALND) is indicated when there are three or more positive lymph nodes found in patients with small (≤5 cm) tumors (T1 or T2), any number of positive lymph nodes found in patients with large (>5 cm) tumors (T3) or extranodal extension of tumor cells, and any number of positive lymph nodes found in those who will not undergo whole breast irradiation. (See 'Indications' above.)

●Anatomy – The surgeon must understand the complex anatomy of the axilla in order to preserve maximum muscular function and sensation. The level of the ALND is defined by anatomic location. Axillary lymph nodes are divided into three levels based upon their relationship to the pectoralis minor muscle. (See 'Surgical anatomy' above.)

●Surgical technique – An ALND is usually performed through a small incision, and confirmation of the anatomic landmarks is crucial for avoiding injuries with functional consequences. (See 'Surgical technique' above.)

●Complications – The anatomic disruption caused by the ALND may result in lymphedema, nerve injury, and shoulder dysfunction, which compromise functionality and quality of life. (See 'Complications' above.)