Review
Sentinel lymph node sampling in gynaecological cancers: Techniques and clinical applications

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Abstract

Background

The sentinel lymph node (SLN) is defined as the first node in the lymphatic basin that receives primary lymphatic flow. If the SLN is negative for metastatic disease, then other nodes are expected to be disease-free. Sentinel node techniques have received widespread application in the staging and treatment of many tumours including melanoma, breast and vulval cancers. The aim of this review is to evaluate the technique and the prognostic significance of the SLN concept in gynaecological malignancies.

Methods

A comprehensive computer literature search to identify relevant articles on SLN biopsy in women with gynaecological cancer. MEDLINE and EMBASE databases up to 2008 were searched for the following terms: “vulva, cervix, uterine, ovarian, neoplasm, carcinoma, lymph node metastases, sentinel node, technique, and prognosis” as medical subject headings (MeSH). Articles selected included reviews, clinical studies, letters, comments, conference proceedings, unpublished data and case reports. Non-English articles were excluded.

Results

Variation in the detection methods of SLN was observed among the studied literature. Large trials have been concluded for both vulval and cervical cancers showing improved detection of SLNs with the added advantage of decreased morbidity. The detection protocol of SLN in endometrial cancer is yet to be refined. Less work has been observed with regards to the SLN sampling in ovarian tumours.

Conclusions

The SLN procedure appears to reliably predict the metastatic status of the regional lymphatic basin in patients with vulval and cervical cancers. More work is needed to establish the role of SLN sampling in endometrial and ovarian cancers.

Introduction

The sentinel lymph node (SLN) is defined as the first node in the lymphatic basin that receives primary lymphatic flow. The identification and subsequent pathological examination of the sentinel node(s) is an indication of the nodal status of the remaining nodes. Patients with negative SLN may be spared complete surgical dissection of all draining nodes in order to decrease the morbidity of this major surgical intervention.

Cabanas first hypothesised in penile carcinoma that the lymphatic channels draining into the iliac lymph nodes drain first into the sentinel lymph node and importantly that the inguinal-femoral lymph nodes were never involved in the absence of its involvement.1 The concept of sentinel lymph node mapping is already established in the surgical management of some tumours such as melanoma2, 3, 4 and breast carcinoma.5, 6 The utility of this important technique is now becoming established as part of the standard management of some gynaecological cancers.

Section snippets

Mapping methods

There are two methods described for SLN identification: vital stains and radioactive isotopes.

Pathological handling of sentinel lymph nodes

Retrospective studies of recurrence in patients whose sentinel nodes were reported as negative on conventional pathologic examination revealed subtle tumour cells in approximately 12% of the patients on further evaluation.15, 16 These observations highlighted the importance of detailed pathological assessment of SLN(s).

So far, there has been no established protocol for histopathological assessment of SLNs in gynaecological malignancy. For breast carcinomas, The Royal College of Pathologists

Background

Squamous cell cancer (SCC) of the vulva is a rare disease with an annual incidence of 2–3 per 100,000 women.21 More than 1000 new cases of vulval cancer were reported in the UK in 2000 (incidence rate of 1.7/100,000 women). The disease was ranked as the 20th most common cancer in women. The mortality figures in 2002 recorded 364 deaths for all age groups (death rate of 1.2/10,0000 women).22

The majority of these patients have tumours limited to the vulva at the time of presentation.21, 23

Background

Cervical carcinoma is the commonest gynaecological cancer worldwide with approximately 500,000 new cases per year and is particularly prevalent in developing countries.45 The UK incidence is approximately 3000 cases per year accounting for over 1000 deaths annually (Cancer Research UK, Cancer Incidence Statistics 2002).

The standard surgical treatment for early stage clinically apparent cervical cancer usually comprises radical hysterectomy with pelvic and/or para-aortic lymphadenectomy.46

Background

The incidence of endometrial cancer has shown an increasing trend in industrialised countries. In the UK, 6000 new patients with endometrial cancer are diagnosed every year, with a yearly mortality rate of 1500 (Cancer Research UK). In the USA, endometrial cancer is the most common female cancer. In 2004, the number of estimated new cases was 40,320 and 7090 deaths were expected.62 The incidence of endometrial cancer is low in women under the age of 40 years (<2/100,000), rising significantly

Ovarian cancer

The incidence of positive lymph nodes in patients with early stage ovarian cancer is 5.1–15%.78 Hence, the majority of patients who undergo para-aortic or pelvic lymphadenectomy would not benefit from the procedure. Moreover, this procedure is associated with increased operative time, blood loss and a significant risk of lymphocyst formation. Furthermore, previous studies failed to demonstrate survival benefit of lymphadenectomy to patients with early stage ovarian epithelial cancer.

Para-aortic

Conclusion

Sentinel lymph node mapping has gained popularity in gynaecological oncology. The evaluation of SLN(s) identifies patients without nodal involvement/metastases, who could benefit from limited surgery and thereby reducing the associated risk of lymphodema. Those with metastatic nodal disease might benefit from additional therapy such as complete lymphadenectomy or adjuvant treatment.

Currently, the technique of SLN biopsy is widely applicable to vulval and cervical cancers. However, in ovarian

Conflict of interest

The authors have no conflict of interest.

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