Sentinel lymph node mapping in endometrial cancer: a literature review and state of the art

Objective: Sentinel lymph node biopsy has proven safe and feasible in a number of gynecologic cancers such as vulvar cancer, cervical cancer, and endometrial cancer. The aim of sentinel node mapping is to decrease the morbidity associated with a complete lymphadenectomy, while also increasing the detection rate of small lymph node metastases. The scope of this review is to critically appraise the published literature on (Sentinel Lymph Node) SLN procedure in endometrial cancer (EC). Methods: We run a PubMed search for publications in English using “endometrial cancer” and “sentinel node” as key words. All abstracts from 2005 to December 2015 were reviewed. We excluded studies aimed to determine the risk of metastasis in the remaining non-SLNs when the SLN is positive, studies that only reported on successfully mapped patients, those where different types of gynecological cancers other than EC and/ or atypical endometrial hyperplasia were included and those studies with less than 30 cases. Results: 23 studies met the inclusion criteria. The overall detection rate of sentinel nodes after cervical injection ranged from 62% to 100%, while it was 73% to 95% after corporeal injection. All studies with n of cases ≥ 100 had overall detection rates of >80%. In terms of product/tracer used, Technetium colloid, blue dye and ICG were used either alone or in combination. Detection rates were good for all three products, however, detection rates were higher when blue dye was combined with Technetium (Tc) or Indocyanine Green (ICG). The injection site influenced the pattern of sentinel mapping with para-aortic SLNs being found more often using corporeal and deeper (3–4 cm) cervical injection techniques. Studies in which the protocol included a systematic para-aortic lymphadenectomy had higher detection of para-aortic SLNs, as well as isolated para-aortic metastases. Conclusion: Sentinel lymph node mapping for endometrial cancer balances the need to assess nodal disease with the low likelihood of nodal metastasis for most patients. It is a technique with minimal morbidity, sparing the need for a full lymphadenectomy and its associated higher morbidity potentially leading to a greater utilization by gynecologic surgeons in the future. Achieving high bilateral SLN detection rates and low false-negative rates is mandatory to implement the SLN mapping as a routine component of clinical practice.