Population-level uptake of neoadjuvant chemotherapy for stage IVB endometrial cancer.

OBJECTIVE:To examine population-level trends, characteristics, and outcomes of patients with stage IVB endometrial cancer who received neoadjuvant chemotherapy (NACT) prior to surgery. METHODS:The National Cancer Institute's Surveillance, Epidemiology, and End Results Program was retrospectively queried by examining 5505 patients with stage IVB endometrial cancer from 2010 to 2018. Exposure allocation was per treatment: primary surgery followed by chemotherapy (n = 3052, 55.4%), NACT followed by surgery (n = 930, 16.9%), and chemotherapy alone (n = 1523, 27.7%). Main outcomes measured were (i) the trend of utilization of NACT and patient characteristics related to NACT assessed with multinomial regression analysis and (ii) overall survival (OS) assessed with multivariable Cox proportional hazards regression model. RESULTS:The number of patients receiving NACT prior to surgery increased from 11.6% to 21.7% whereas those undergoing primary surgery followed by chemotherapy decreased from 62.7% to 48.3% (P < 0.001). Increasing utilization of NACT remained independent in multivariable analysis (adjusted-odds ratio per one-year increments 1.11, 95% confidence interval [CI] 1.08-1.15). Increasing utilization of NACT was observed in several sub-cohorts including patients aged <65 years, ≥65 years, White, non-White, endometrioid, non-endometrioid, and cases with non-distant organ metastasis (P < 0.05). In a multivariable analysis, NACT followed by surgery and primary surgery followed by chemotherapy had comparable OS (median 25 versus 26 months, adjusted-hazard ratio [HR] 1.03, 95%CI 0.93-1.15). When examined for metastatic extent, NACT followed by surgery was associated with decreased OS compared to primary surgery followed by chemotherapy in the non-distant organ metastasis group (adjusted-HR 1.20, 95%CI 1.05-1.36) whereas it was associated with improved OS in the distant organ metastasis group (adjusted-HR 0.79, 95%CI 0.66-0.95). CONCLUSION:The treatment of stage IVB endometrial cancer is shifting from primary surgery to NACT in the United States.