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Sentinel node biopsy: modern minimal invasive surgery to stage the axilla



Breast cancer is the most common diagnosed malignancy in the UK, with 40,000 new cases causing 13,000 deaths per annum. Early detection and specialised treatment have resulted in improved survival from breast cancer. Breast conservation surgery for cancer is now established and there is conclusive evidence that conservative surgery to the axilla is also the standard of care.

Women with involved axillary nodes fall into a worse prognostic category.1 Broadening indications for systemic therapy may result in a clinical decision to offer women chemotherapy based on the pathology of the primary tumour such as high tumour grade, the presence of lympho-vascular invasion and hormone receptor resistance, with less emphasis on the axillary node status. Prior to sentinel node biopsy, there was no reliable test to distinguish the presence or absence of axillary regional metastasis without an operation to remove en-bloc the lymph nodes within the axilla for pathological assessment. From a therapeutic aspect, total removal of the axillary nodes will only be useful in a patient who is node positive. Standard staging of the axilla was once considered to be formal block dissection of the lymph nodes. As only 20-40% of women with early breast cancer are likely to be node positive, 60-80% of women receiving axillary dissection as a blanket means of axillary staging would have been over-treated. As axillary dissection involves removal of most of the lymph nodes within the armpit, this form of surgery is associated with a higher adverse risk of morbidity following treatment including recurrent seromas, shoulder stiffness, chronic pain and lymphoedema.2

The advantages of sentinel node biopsy

Sentinel node biopsy allows women who are identified to be node positive to be selected for axillary dissection as a therapeutic procedure. As a minimally invasive technique, sentinel node biopsy is a very targeted and accurate means of staging the axilla.3-5 Only women identified to be node positive on sentinel node biopsy require a therapeutic or full axillary dissection. The majority of women that are node negative can therefore have conservative surgery to the axilla with a shorter recovery time from surgery and much lower risk of complications. Sentinel node biopsy as a procedure thus answers the question as to whether the axilla is staged as positive for cancer metastasis or is clear of disease.6 A negative finding allows the rest of the axilla to be left undisturbed whilst a positive finding enables axillary surgery to be tailored to suit the individual needs of patients. Sentinel node biopsy can be considered the next generation of modern conservative axillary surgery that is highly accurate and is associated with very low morbidity.7 Its place in the management of early breast cancer as a means of staging the axilla is now well established.

Alternative conservative surgical approaches to the axilla

Prior to sentinel node biopsy, random axillary sampling was the only conservative approach to the axilla, consisting of an undirected process of selecting several nodes, typical four, to stage the axilla. Axillary sampling was practised only in a minority of centres outside specialist units as the credibility of random sampling was considered to be questionable and irreproducible. Like sentinel node biopsy, women with a positive four node axillary sample can be selected for therapeutic axillary management.8

The procedure

The sentinel node biopsy is performed by initially injecting the affected breast with a 99technetium radioactive isotope that is taken up into afferent lymphatic channels that drain into the lymph glands. A gamma camera scan is then taken with images to determine the site and numbers of nodes. Sentinel nodes that may reside in the internal mammary chain or within the breast substance can be detected, that would otherwise have been missed without the radio-isotope localisation. The commonest injection techniques is into the subareolar tissue in the quadrant of the breast where the tumour is sited. At the time of surgery a vital blue dye is injected into the same site that is also taken up into the lymphatic system and retained by the sentinel node. The sentinel node can then be identified at surgery by vision as a blue node and also by a special hand held gamma probe to detect radioactivity from the isotope injection. Most breast specialists recommend using both the radioisotope and blue dye techniques for the highest accuracy levels from the sentinel node technique.5

Patient selection

Women diagnosed with early breast cancer that who do not have abnormal lymph nodes in the axilla on physical examination or imaging are suitable for sentinel node biopsy. Specific circumstances should be discussed with your breast surgeon. Women should be counselled about the full implications about sentinel node biopsies. Like all medical investigative procedures, there is a small false negative and technical failure rate. When considering the competing risks versus benefits between the various approaches to the axilla in early breast cancer, the balance usually falls in favour of sentinel node biopsy as an accurate means of axillary staging in most women.

The future

There are ongoing trials to evaluate how best to manage women with positive sentinel nodes. This future development is important as in up to 50% of patients, a positive sentinel lymph node may be only involved node within the axilla. Until the results of clinical trials become available, woman with a positive sentinel node biopsy are usually recommended to have a completion axillary dissection. Future developments include improving intra-operative assessment of the sentinel node that might facilitate definitive axillary surgery in those found to have a positive sentinel node, thus avoiding need for a subsequent operation.


All surgeons who undertake sentinel node biopsy should have been trained and validated in the technique. There is a clear learning curve to become skilled in this procedure.


Just as breast conservation surgery has been shown to have an equivalent survival outcome to mastectomy and has become standard surgical treatment for early breast cancer, sentinel node biopsy may enable conservative surgery to the axilla, selecting women for positive nodes only for full axillary treatment. The morbidity of unnecessary axillary dissection as a staging procedure may thus be reduced. Further clinical trials are awaited before other treatment options become available for the positive sentinel node biopsy.


Fisher B, Slack NH. Number of lymph nodes examined and the prognosis of breast cancer. Surg Gynecol Obstet 1970; 131: 79-88.
Ivens D, Hoe AL, Podd TJ, et al. Assessment of morbidity from complete axillary dissection. Br J Cancer; 66: 136-138.
Guiliano AE, Kirgan DM, Guenther SM, Morton DL. Lymphatic mapping and sentinel lymphadenectomy for breast cancer. Ann Surg 1994; 220: 391-398.
Krag DN, Weaver DL, Alex JC, Fairbank ST. Surgical resection and radiolocalisation of sentinel lymph nodes in breast cancer using a gamma probe. Surg Oncol 1993; 2: 335-339.
Schwartz GF, Guiliano AE, Veronesi U, the Consensus Conference Committee. Proceedings of the Consensus Conferenceof the Role of Sentinel Lymph Node Biopsy in Carcinoma of the Breast, April 19-22, 2001, Philadelphia, Pennsylvania. Cancer 2002; 94: 2542-2551.
Krag DN, Julian TB, Harlow SP, et al. Phase III randomised trial comparing axillary resection with sentinel lymph node dissection: a description of the trial. Ann Surg Oncol 2004; 11: 208S-210S.
Purushotham AD, Upponi S, Klevesath MB, et al. Morbidity after sentinel lymph node biopsy in primary breast cancer: results from a randomized controlled trial. J Clin Oncol 2005;23: 4312-21.
Chetty U, Jack W, Prescott RJ, Tyler C, Rodger A. Management of the axilla in patients with operable breast cancer treated by breast conservation: a randomised trial. Br J Surg 2000; 87; 163-9.

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