Axillary lymph nodes

Treatment of the axillary lymph nodes

The lymphatic drainage of the breast has already been described in some detail (see previous section). It is essential to have an accurate histological assessment of the lymph nodes in the axilla because this will provide prognostic information about the disease (and determine the need for adjuvant therapies) and is also required to achieve adequate 'regional' control of disease. Clinical assessment of the axillary node status is most unreliable, in some studies less than 60% of involved nodes are clinically detectable. Radiological imaging procedures (mammography and ultrasound) do not reliably detect tumour-involved lymph nodes. Although magnetic resonance imaging and positron-emission tomography have shown some promise they are not used in routine pre-operative assessment of the axilla. Therefore, some form of axillary surgery to remove the lymph nodes and examine them histologi-cally is the only way, at present, of accurately determining if they are involved with tumour. There are various surgical approaches (i.e. axillary sample, dissection and clearance).

Axillary sample

This involves the removal of four or more lymph nodes (confirmed at operation) from the proximal anterior/pectoral and central group of draining lymph nodes in the axilla. This has been shown to provide an accurate assessment of the nodal status of the axilla. Some surgeons, however, have had difficulty in identifying the required number of lymph nodes and have questioned whether sampling is an adequate procedure to stage the axilla. If the sampled nodes contain malignant cells, then radiotherapy to the axilla and supra-clavicular areas (4500 cGy) is given. The internal thoracic group of lymph nodes should also be considered. It has been estimated that approximately 90% of women with internal thoracic node involvement also have axillary nodes involved with tumour. If there is a strong possibility of tumour spread to the internal mammary group of lymph nodes (e.g. from tumours in the medial aspect of the breast), these nodes can also be irradiated.

Axillary dissection

An alternative approach to axillary node sample is dissection of the axilla to various anatomical levels, as outlined below:

Level 1: removal of lymph nodes lateral to the inferior border of the pectoralis minor muscle.

Level 2: removal of level 1 lymph nodes and those behind and in front of pectoralis minor muscle. Neither a level 1 nor 2 dissection of the axilla is an adequate therapeutic manoeuvre on its own. For example, if level 1 nodes are involved there is a 10% chance of further nodal involvement at level 2 or 3; if level 2 nodes are involved there is a 50% chance of level 3 nodes being involved with tumour. Radiotherapy to the axilla, therefore, is also required in patients with involved lymph nodes and who have undergone level 1 or 2 dissections. The likelihood of lymphoedema is significantly increased with irradiation of the axilla following axillary dissection.

Axillary clearance

This is the removal of all the axillary lymphatic tissue (also termed a level 3 axillary dissection). In order to achieve this, division or removal of the pectoralis minor muscle allows better access to the upper aspect of the axilla. The axillary contents (fat, fascia, lymphatic tissue) are cleared, starting from the apex (outer border of the first rib), below and medial to the axillary vein. The brachial plexus, the major axillary vessels, the long thoracic nerve and the thoracodorsal vessels and nerve are preserved during dissection. With a thorough axillary clearance no further treatment of the axilla is required, irrespective of whether there is involvement of the lymph nodes by tumour. Radiotherapy to the axilla following a clearance is associated with up to 30% incidence of lymphoedema. However, this does not result in a substantial improvement in regional disease control. Axillary surgery is not recommended for DCIS or minimal cancers.

Sentinal lymph node biopsy

Recently, the use of sentinal node biopsy has been advocated for patients with invasive breast cancer. The theoretical basis of this technique is that the malignant cells will desiminate in an orderly fashion to the axillary nodes, spreading firstly to the 'sentinal' lymph node. Therefore, by removing this lymph node for histological examination a representative view of the state of axillary nodal involvement can be achieved with the minimum of disruption to the axilla itself.

There are different techniques which are available to localise the sentinal node, but basically either an injection of a radiocolloid and/or a vital blue dye is given to the patient either per-itumourally or subdermally (usually in the periareolar region).

At the time of surgery, the sentinal node can then be localised using a probe to detect the radioactively labelled colloid which has accumulated in it and the site marked. Through a small incision the sentinal node(s) are located and if the blue dye has also used, this will give a further visual identification of the sentinal node.

A recent meta-analysis of more than 60 studies of sentinal node biopsy has suggested that there is a false negative rate of approximately 8% with this procedure, and in studies of smaller numbers of patients it was even higher at up to 25%. In some centres sentinal nodes are examined using 'frozen sections', or by imprint cytology and if there is evidence of metastatic tumour in the node, an axillary clearance can be carried out immediately. This removes the requirement for a patient to undergo a second operative procedure.

However, whilst the technique has been adopted widely in surgical practice the evidence from a randomised-controlled trial that it is as effective and efficient as axillary sampling is still awaited.

Morbidity of axillary treatment

Axillary surgery and radiotherapy are associated with a recognised morbidity. During surgery, there is the risk of damage to nerves, most commonly the intercostobrachial nerve, not

Figure 17.28. An example of lymphoedema of the arm following axillary clearance (level 3).

infrequently cut and resulting in anaesthesia and/or paraes-thesia of axilla and inner aspect of upper arm. The long thoracic and thoracodorsal nerves may also be damaged on occasions. Furthermore, wound seromas or infections may occur in up to 5% of patients. Radiotherapy may also be associated with nerve damage, and more rarely a brachial plexopa-thy. Both radiotherapy and surgery are associated with some reduction in the range of movements at the shoulder joint (particularly in elderly patients). Less than 10% of patients will develop lymphoedema (variable degree) following radiotherapy or a level 2 or 3 axillary dissection (Fig. 17.28).

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