ReviewSentinel lymph node sampling in gynaecological cancers: Techniques and clinical applications
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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Cited by (42)
Sentinel Node Mapping in Gynecologic Cancers: A Comprehensive Review
2019, Seminars in Nuclear MedicineCitation Excerpt :However, the injection into both ovarian ligaments shows a quite similar detection rate of SLN (90%-100%). In case of injection in the cortex, a lower detection rate is observed (40%-100%), with a higher risk of capsule rupture and tumor dissemination during surgery.161 Although the exact timing for the intraoperative detection of positive LNs remains undefined, it seems that 10-20 minutes is an optimal time interval between radiopharmaceutical injection and SLN detection,154,162-164 with excellent SLN detection rate (100%, 94%, 96%); furthermore, it was showed that in case of injection of [99mTc phytate], a waiting time of 10 minutes is sufficient, with a detection rate of 84%.164
Sentinel-node biopsy in early-stage ovarian cancer: preliminary results of a prospective multicentre study (SELLY)
2019, American Journal of Obstetrics and GynecologyThe Application of Sentinel Lymph Node Biopsy in Cervical Cancer
2018, Principles of Gynecologic Oncology SurgeryReal-time near-infrared fluorescence guided surgery in gynecologic oncology: A review of the current state of the art
2014, Gynecologic OncologyCitation Excerpt :Furthermore, radioisotopes can only be detected using a gamma counter, but real-time intraoperative visual guidance to exactly locate the SLN is lacking. When intraoperatively searching for the SLN, the radioactive signal can be disturbed by a high background signal originating from the injection spot around the vulvar tumor (shine effect) [12]. In recent years, NIR fluorescence imaging has been introduced in SLN mapping in vulvar cancer, because this technique has the potential for accurate, real-time, intraoperative SLN mapping [1] (Fig. 1).
Intraoperative imaging
2013, Best Practice and Research: Clinical Obstetrics and GynaecologyCitation Excerpt :The sentinel lymph node (SLN) is defined as the first node in the lymphatic chain that receives primary lymphatic flow. Its identification and histopathological examination signifies the nodal status of the distal draining nodes.52 The extent of cancer surgery is considerably affected if SLN are affected or not.
Preoperative sentinel node mapping with <sup>99m</sup>Tc-nanocolloid SPECT-CT significantly reduces the intraoperative sentinel node retrieval time in robot assisted laparoscopic cervical cancer surgery
2013, Gynecologic OncologyCitation Excerpt :Furthermore, the five-year disease specific survival is reduced to 61.8% compared to 94.4% in node negative patients [4]. Sentinel node (SN) procedures in cervical cancer are an increasingly well evaluated patient-tailored practice to assess lymph nodal status at the onset of surgical treatment [1,5–8]. When performed correctly, false negative rates of 1.3% are achieved [8].