Axillary dissection is a surgical procedure that incises the axilla to identify, examine, or remove lymph nodes. Axillary dissection has been the standard technique used in the staging and treatment of the axilla in breast cancer. Patients presenting with symptomatic early breast cancer have a 30-40% chance of having positive axillary nodes and 20-25% chance if presenting through a screening program.
Staging of the axilla is an important step in the treatment of breast carcinoma. Axillary lymph node status is a significant prognostic pathologic variable in patients with operable primary breast cancer, and it remains the most powerful predictor of recurrence and survival. The number of lymph nodes with metastasis also has prognostic importance. [1, 2]
Axillary dissection was first advocated as part of the treatment of invasive breast cancer in the 18th century by Lorenz Heister, a German surgeon. [3, 4, 5] In modern practice, the role and benefits of axillary dissection have been influenced by the National Surgical Adjuvant Breast Project B-04 trial,  which concluded that axillary dissection has no effect on survival. However, other studies provided substantial evidence that axillary dissection provides excellent local control of disease in the axilla, with a local recurrence rate of 2% or less, [7, 8] which may lead to improved overall survival. [9, 10]
Axillary dissection should be reserved for patients with proven axillary disease preoperatively or with a positive sentinel node biopsy.
Axillary dissection is only therapeutic in patients who are node positive. Therefore, performing axillary dissection in all patients would lead to an overtreatment of at least 60% of patients who are all node negative. The introduction of sentinel-node biopsy has changed the approach to the axilla, as the status of the axilla can be established with less morbidity for patients when compared with complete axillary dissection.
There may be a gradual shift away from carrying out an axillary clearance in patients with positive sentinel nodes. A recent trial (AMAROS), presented at the Annual Meeting of American Society of Clinical Oncology, compared the use of axillary radiotherapy with axillary clearance in patients who had a positive sentinel node and found no significant difference in disease-free or overall survival, but reduced lymphoedema rates in the radiation group.
Results from the American College of Surgeons Oncology Group (ACOSOG) Trial (Z0011) reported patients without clinical or radiological evidence of axillary metastases undergoing breast-conserving surgery having whole-breast radiotherapy, with positive sentinel nodes, did not achieve any further oncological benefit by having axillary clearance.
There is an increasing use of neoadjuvant chemotherapy in breast cancer, and the optimal timing of sentinel node biopsy can be controversial. Axillary dissection is advocated for all patients who complete neoadjuvant treatment to down-stage the breast tumor, except when sentinel node biopsy is negative and undertaken prior to the neoadjuvant treatment.
Sentinel node biopsy prior to chemotherapy could be considered the most accurate staging assessment of the axilla, while some would argue that performing the sentinel node biopsy after chemotherapy could allow patients who have had a complete pathological response to be spared the increased morbidity of an axillary clearance.
The current National Comprehensive Cancer Network/American Society of Clinical Oncology guidelines still recommend axillary clearance in patients with micrometastatic disease in sentinel nodes, but the benefit of carrying this out routinely has been questioned following studies showing no significant difference in axillary recurrence or survival for patients having sentinel node biopsy only versus completion axillary clearance.
Axillary clearance has no absolute contraindications. As with any elective surgical procedure, patients must be medically optimized and suitable for general anesthesia.
The argument for carrying out axillary dissection in the presence of distant metastases is controversial but may have a role in obtaining locoregional control, if required.
Patients with advanced disease in the axilla with palpable axillary nodes, if proceeding to surgery, generally do not require cytological/histological confirmation of nodal involvement.
Ultrasound assessment of the axilla in combination with either fine needle aspiration or core biopsy can detect a positive axillary node in a large proportion of node-positive cases. This positive preoperative axillary status allows women to proceed directly to axillary dissection, avoiding sentinel node biopsy.
Patients who preoperatively have no evidence of axillary disease should undergo a sentinel node biopsy and have axillary dissection carried out if the sentinel node is positive. This can be carried out during the index operation if the sentinel node can be analyzed intraoperatively using frozen section, imprint cytology, or molecular-based assays.
The axilla is a quadrangular space that lies between the following:
The lower border of the axillary vein superiorly
The chest wall medially
The axillary skin laterally
Pectoralis major and minor anteriorly
Latissimus dorsi, teres major, and subscapularis posteriorly
Axillary dissection removes all the nodes and fat from this space. Although the nodes are in a continuum, the clearance can be anatomically divided into three levels based on the relationship of the tissue to the pectoralis minor muscle.
Patient Education & Consent
The patient can be taught a full range of shoulder exercises preoperatively. The range of shoulder movement should be assessed preoperatively.
Postoperatively, the same exercises are encouraged to ensure full mobility. Patients are generally advised to avoid any heavy lifting with the arm on the side of the cancer, which will potentially reduce risk of lymphoedema and also avoid any unnecessary trauma, including iatrogenic intervention on that arm to reduce risk of infection.
Equipment includes the following:
Standard operating room anaesthesia equipment
A standard general surgical set, including self-retaining retractors
A suction drain
Although sentinel node biopsy can be carried out under local anesthesia, axillary dissection is nearly always carried out under general anesthesia.
Additional local anesthetic is usually injected around the site of axillary incision and can be instilled directly on the remaining axillary structures.
Confirm and mark the correct surgical site preoperatively.
Patients are positioned lying supine, with the arm abducted and placed on an armboard at 90 degrees to the chest wall.
If required, shave the surgical site with electrical clippers. Prepare and drape the surgical site in standard surgical way. The arm can be draped separately in a sleeve to facilitate complete arm movement for the axillary dissection.
The head end is raised to 30 degrees. The shoulder can be flexed to facilitate dissection of axillary level III nodes.
Axillary dissection is not very painful. The patient may feel slight discomfort and soreness at the wound site, which is easily managed by taking mild analgesics.
A slight risk of wound infection exists after breast surgery, which may result in wound breakdown.
Hematoma generally develops within 24 hours after the operation. It is a very rare complication.
Patients may notice swelling of the wound site and bruising over the breast or axilla.
The observed rates of seroma after axillary surgery range from 2.5-51%. It may necessitate needle drainage on one or multiple occasions.
Shoulder stiffness is a temporary and self-limited side effect. Physiotherapy can be beneficial.
Lymphoedema of the arm and breast constitutes a significant long-term sequelae to axillary dissection. This is minimized by limiting the dissection superior to the axillary vein. Studies of reverse axillary mapping may modify the approach to the axilla in the future.
A numb patch on the upper arm may be caused by division of intercostobrachial nerve.
Care should be taken to ensure the long thoracic nerve is visible and protected as the dissection proceeds to the apex of the axilla. It is often retracted away from chest wall towards the specimen with the traction applied.
In cases with excessive nodal involvement, an approach through the interpectoral space is useful. The pectoralis minor is retracted laterally and the pectoralis major medially with the dissection carried out through this space to reach level III. Small vessels at the apex are carefully taken with diathermy.
Axillary dissection can be carried out through the incision for a mastectomy. Patients having lumpectomy usually require a separate incision in the axilla. Often, the preference is for a skin crease incision just below the axillary hairline extending from the posterior edge of the pectoral fold to the posterior axillary line. Flaps are raised off the skin and subcutaneous tissue.
Dissection is carried past the edge of pectoralis major muscle. Retraction of the pectoralis major medially exposes the pectoralis minor and the clavipectoral fascia. The lateral pectoral nerve bundle is identified and preserved. Incision into the clavipectoral fascia allows entry into the axillary fat and the contained nodes. These are removed en bloc through the surgery.
Dissection is carried superiorly along the edge of the pectoralis minor to reach the inferior edge of the axillary vein. Once the axillary vein is identified, this is followed medially to reach the axillary apex, where the axillary vein crosses the lateral border of the first rib.
The axillary contents are then separated from the lateral thoracic wall, which is the medial boundary of the axilla. This exposes the long thoracic nerve, which supplies the serratus anterior muscle (injury to which would lead to winging of the scapula). During this dissection, branches of the intercostobrachial nerve will be identified as they cross the axilla after emerging from the intercostal spaces. The larger trunks should be preserved if possible.
Ligation and division of the smaller tributaries of the axillary vein as they enter the axilla allows visualization and identification of the subscapular vessels and thoracodorsal nerve as they reach the subscapular and latissimus dorsi muscles posteriorly.
The axillary fat and nodal tissue between the long thoracic nerve and the subscapular vascular bundle is carefully dissected. Often, this is performed en bloc with the specimen, although it sometimes can occur separately if there is extensive nodal involvement.
The dissection then proceeds towards the apex to include the nodes medial to the pectoralis minor (Berg level III). This is facilitated by flexion of the free draped arm at the shoulder.
The axillary fat and nodes are finally separated from the axillary tail of the breast to allow the specimen to be excised.
Careful pathological examination for an axillary dissection will often reveal in excess of 20 lymph nodes.
The wound is closed in layers over a suction drain.