Current Role of Sentinel Lymph Node Mapping in Endometrial Cancer

Introduction With the ongoing debate over the appropriate extent of lymph node (LN) dissection for endometrial cancer, sentinel lymph node (SLN) mapping may provide an attractive alternative solution. Since 1996, there have been different injection sites and tracers used to detect the SLN. This review focuses on the different techniques of SLN mapping for endometrial cancer and evaluates the diagnostic accuracy and clinical value. Methods We conducted an electronic database search using three databases (PubMed, EMBASE, and Web of Science) and included only published, original research studies of patients who had undergone SLN mapping for endometrial cancer with an n > 30. Data collected included injection technique, detection rates as well as diagnostic accuracy. Results There were 633 studies found, but only 28 met the inclusion criteria. Eighteen studies utilized a cervical injection method with overall SLN detection rates ranging from 86 to 96 %, bilateral detection rate from 51 to 76 %, and para-aortic detection from 0 to 15 %. Four studies utilized sub-endometrial injection, and another four utilized myometrial injection with lower overall and bilateral SLN detection rates, but higher para-aortic detection. Twenty-four studies were included for evaluation of diagnostic accuracy. In the largest study of 508 patients, SLN mapping had a sensitivity of 98.4% and negative predictive value of 99.7 %. In large studies (n >= 100), the SLN was the only metastatic LN in 35-74 % of cases, and ultrastaging enabled the detection of micrometastatic disease or isolated tumor cells in 30-50 % of cases that would have been missed if only routine hematoxylin and eosin staining had been used. Conclusions SLN mapping for endometrial cancer appears promising, with a high negative predictive value. The SLN is the most likely node involved with metastatic disease, and these nodes are sometimes found in areas not usually sampled during standard lymphadenectomy. Future studies will need to examine the impact and value of SLN biopsy on adjuvant therapy and survival.