Sentinel lymph node mapping detection and recurrence rates in clinical stage I endometrial cancer

Objectives: The literature suggests that sentinel lymph node biopsy (SLNB) is an acceptable alternative to pelvic and paraaortic lymph node dissection (PPALND) in patients with clinical stage I endometrial cancers. The referenced data is largely published from high-volume specialized institutions and a complete PPALND is still performed by many surgeons at smaller, non-specialized centers. Our aim is to demonstrate that SLNB is feasible, reproducible, and sensitive without affecting cancer-specific outcomes when implemented at a non-specialized center. Methods: A retrospective review of patients with clinical stage I endometrial cancer was performed from September 2016 through February 2020. All patients had undergone either a robot-assisted or laparoscopic hysterectomy with SLNB. Endometrioid, uterine papillary serous (UPSC), malignant mixed mesodermal tumor (MMMT), and clear cell (CC) histologies were included. Indocyanine green was injected into the cervix bilaterally as per a previously described protocol. Paraaortic LND was performed at the discretion of the surgeon. In addition to SLNB, complete PPALND was performed for patients with MMMT, UPSC or CC. Sentinel lymph nodes (SLN) were evaluated using ultra-staging protocols including serial sectioning and cytokeratin staining. The medical record was queried for clinical or radiographic evidence of recurrence. Results: A total of 92 patients were included: 69 stage IA, 12 stage IB, 3 stage II and 8 stage III (2 IIIA, 2 IIIC1, 4 IIIC2). The majority of patients were endometrioid (73%), followed by UPSC (15.0%), MMMT (5.0%) and CC (4%). At least one SLN was detected in 95.4% of cases. The rate of bilateral SLN detection was 74.3% and improved over time from 2017-2019: 70% (2017), 74.4% (2018), 80% (2019). Twenty patients underwent PPALND. Non-SLN were positive in 3 patients, all with high-risk histology. There were no other patients with false-negative SLNB. There have been 3 (3%) recurrences to date; one rectal recurrence, one pelvic side wall and one paraaortic lymph node recurrence. All three patients had detected bilateral SLN which were negative at the time of their initial surgery; all three recurrences were high grade histology. Conclusions: SLNB is a sensitive and specific method for assessing lymph node involvement in patients with clinical stage I endometrial cancers. Our detection and recurrence rates are comparable to the rates reported in the literature and demonstrate that when applied at non-specialized centers this approach is safe and reproducible without affecting cancer-specific outcomes.