A Prospective Study of Sentinel Lymph Node Mapping for Endometrial Cancer: Is It Effective in High-Risk Subtypes?

Background The efficacy of sentinel lymph node (SLN) mapping for high-risk endometrial cancer remains unclear. This prompted us to evaluate the sensitivity, negative predictive value (NPV), and false-negative (FN) rate of cervical injection of indocyanine green (ICG) SLN mapping in patients with endometrial cancer. Materials and Methods This prospective interventional study was performed at a single university teaching hospital. Consecutive patients with early-stage endometrial cancer who underwent laparoscopic surgical staging were included. Cervical injection of ICG and near-infrared SLN identification and biopsy were performed for all study patients followed by systematic pelvic lymphadenectomy, whereas para-aortic lymphadenectomy was performed in all patients with high-risk histologies. SLN detection rates, sensitivity, NPV, and FN rates were calculated. Results Between July 2016 and July 2018, 131 patients were enrolled. The overall SLN detection rate was 93.1%, with a bilateral detection rate of 61.8%. Four positive SLNs were identified in four patients. Lymph node metastasis was observed in four additional patients without positive SLNs. These four patients belonged to a group of patients with a high-risk subtype. Three of the four patients had isolated para-aortic node metastases. In low-risk endometrial cancers, the sensitivity of the SLN technique to identify nodal metastatic disease was 100% (95% confidence interval [CI] 31.0-100), with an NPV and FN rate of 100% (95% CI 95.1-100) and 0%, respectively. In high-risk endometrial cancers, the sensitivity, NPV, and FN rate were 20% (95% CI 1.0-70.1), 83.3% (95% CI 61.8-94.5), and 80%, respectively. Conclusion Cervical injection of ICG and SLN mapping yielded a low sensitivity and a high FN rate for the identification of node metastasis in endometrial cancer with high-risk histologies. Implications for Practice The efficacy of sentinel lymph node (SLN) mapping for high-risk endometrial cancer remains unclear. This study enrolled 131 patients with early-stage endometrial cancer who underwent cervical injection of indocyanine green SLN mapping followed by systematic pelvic lymphadenectomy and para-aortic lymphadenectomy. The key result was that SLN mapping yielded a low sensitivity and a high false-negative rate for the identification of node metastasis in endometrial cancer with high-risk histologies. The SLN strategy in these patients may increase the risk of missed diagnosis of isolated para-aortic node metastases and seems to be unacceptable in clinical practice.