Performance of sentinel lymph node biopsy in high-risk endometrial cancer

To determine the rate and performance of sentinel lymph node (SLN) mapping among women with high-risk endometrial cancers.

Patients diagnosed between 2012 and 2015 with uterine cancer of grade 3 endometrioid, clear cell, serous or carcinosarcoma histology and who underwent SLN mapping prior to full pelvic lymph node dissection were included. Subjects underwent methylene blue or ICG injection for laparoscopic (N = 16) or robotic-assisted laparoscopic (N = 20) staging. Outcomes included SLN mapping rates, SLN and non-SLN positive rates, false negative SLN algorithm rate, and the negative predictive value (NPV) of the SLN algorithm. Fisher's exact test was used to compare mapping and node positivity rates.

9/36 (25%) patients with high-risk uterine cancer had at least one metastatic lymph node identified. Successful mapping occurred in 30/36 (83%) patients. SLN mapped to pelvic nodes bilaterally in 20 (56%), unilaterally in 9 (25%), and aortic nodes only in 1 (3%). Malignancy was identified in 14/95 (15%) of all sentinel nodes and 12/775 (1.5%) of all non-sentinel nodes (p < 0.001). The false negative rate of SLN mapping alone was 2/26 (7.7%); the NPV was 92.3%. When the SLN algorithm was applied retrospectively the false negative rate was 0/31 (0%); the NPV was 100%.

SLN mapping rates for high-risk cancers are slightly lower than in prior reports of lower risk cancers. The NPV of the SLN mapping alone is 92% and rises to 100% when the SLN algorithm is applied. Such results are acceptable and consistent with larger subsets of lower risk endometrial cancers.