Sentinel lymph node biopsy for stage II endometrial cancer: Recent utilization and outcome in the United States.

OBJECTIVE: To examine trends and outcomes related to sentinel lymph node (SLN) biopsy for stage II endometrial cancer. METHODS: This is a retrospective observational cohort study querying the National Cancer Institute's Surveillance, Epidemiology, and End Results Program. The study population was 6,314 women with T2 endometrial cancer who underwent hysterectomy from 2010-2018. Exposure allocation was based on nodal evaluation type: lymphadenectomy (LND; n=4,915, 77.8%), SLN biopsy (n=340, 5.4%), or no surgical nodal evaluation (n=1,059, 16.8%). The main outcomes were (i) trends and characteristics related to nodal evaluation assessed by multinomial regression, and (ii) overall survival (OS) assessed by an inverse probability of treatment weighting propensity score analysis. A sensitivity analysis was performed to examine concurrent LND in women who underwent SLN biopsy. RESULTS: The utilization of SLN biopsy increased from 1.6% to 16.1%, while the number of LND decreased from 81.5% to 65.7% between 2010-2018 (P<0.05). In multivariable analysis, the utilization of SLN biopsy increased 45% annually (adjusted-odds ratio 1.45, 95% confidence interval [CI] 1.37-1.54, P<0.001). The frequency of SLN biopsy alone exceeded the frequency of SLN biopsy with concurrent LND in 2017 (6.8% versus 3.4%), followed by continued increase in SLN biopsy alone (11.2% versus 4.9%) in 2018. In the weighted model, the 3-year OS rate was 79.9% for the SLN biopsy group and 78.6% for the LND group (hazard ratio 0.98, 95%Cl 0.80-1.20, P=0.831). Similarly, the SLN biopsy alone without concurrent LND had comparable OS compared to the LND group (hazard ratio 0.90, 95%CI 0.59-1.36, P=0.615). CONCLUSION: Utilization of SLN biopsy in stage II endometrial cancer increased significantly over time, and SLN biopsy-incorporated nodal assessment was not associated with worsened short-term survival outcome.