Learning curve and determinants of sentinel lymph node mapping outcomes in endometrial cancer: A single-center CUSUM analysis

OBJECTIVE: To evaluate the learning curve of sentinel lymph node (SLN) mapping in endometrial cancer and to identify predictors of mapping failure in a single-center experience. MATERIALS AND METHODS: We retrospectively analyzed 59 patients with clinically early-stage endometrial cancer who underwent minimally invasive staging with SLN mapping at Cathay General Hospital between August 2021 and February 2025. Cumulative bilateral detection rates and cumulative sum (CUSUM) analyses were applied to assess the learning curve. Clinical, surgical, and pathological factors associated with mapping failure were examined by univariate analysis. Endometrioid histology comprised 95% of cases, and 81% were 2023 FIGO stage I. The overall detection rate was 92.3%, with bilateral mapping in 69.5%, unilateral mapping in 23.7%, and complete failure in 6.8%. Bilateral detection improved from 65% in the early phase (cases 1-20) to 72% in the late phase (cases 21-59). CUSUM indicated proficiency after ∼38 cases, with stabilization projected at ∼65 cases. Observed mapping failures were often associated with inadequate dye migration or empty specimens. Adnexal adhesions showed a borderline association with bilateral mapping failure (p = 0.080), whereas age, BMI, histologic grade, lymphovascular invasion, and stage were not significant. CONCLUSION: SLN mapping in endometrial cancer exhibits a distinct learning curve, with proficiency achieved after approximately 40-65 cases. Adhesions encountered during surgery, particularly adnexal adhesions, may represent a key technical barrier, underscoring the importance of structured training, standardized protocols, and meticulous surgical management to optimize mapping outcomes.