Objectives: Uterine leiomyosarcoma (LMS) is a rare and extremely aggressive tumor with a high recurrence rate and low disease-specific survival. Treatment involves surgical resection of all visible disease. Adjuvant therapy, however, remains controversial as clinical trial accrual has been low given the rarity of the tumor. NCCN guidelines currently recommend consideration of systemic chemotherapy and/or consideration of external beam radiation therapy after completion of hysterectomy for women with stage II-III LMS. We analyzed the utilization of adjuvant chemotherapy and radiation therapy for stage II and III LMS and explored the association between use of adjuvant therapy and survival. Methods: Patients who had pathologically confirmed stage II or III LMS treated from 2004 - 2016 and recorded in the National Cancer Database (NCDB) were identified. Multivariable regression models were fit to estimate predictors of use of either adjuvant radiation therapy or chemotherapy. To analyze the impact of chemotherapy on all-cause mortality, an inverse probability of treatment weighted (IPTW) propensity score method was used to account for measured confounders. The IPTW outcome model was fit adjusting for the receipt of radiation therapy. The process was repeated to analyze the impact of radiation therapy on all-cause mortality by using an IPTW propensity score method and adjusting for the receipt of adjuvant chemotherapy in the outcome model. Results: A total of 852 patients were identified. Adjuvant chemotherapy and radiation therapy were utilized in 67% and 16% of patients, respectively. Adjuvant chemotherapy use grew from 62% in 2010 to 70% in 2016, whereas radiation usage decreased from 27% in 2010 to 10% in 2016. Patients with stage III (vs stage II) disease and tumors larger than 10 cm were less likely to receive radiation therapy. Overall 5-year survival for the entire cohort was 27.9% (95% CI 24.0 - 31.9%). After propensity score weighting and adjusting for receipt of chemotherapy, radiation therapy was associated with 41% decreased risk of all-cause mortality (HR 0.59, 95% CI 0.41 - 0.88, Figure 1A). In contrast, after propensity score weighting and adjusting for receipt of radiation therapy, chemotherapy was not associated with mortality (HR 0.88, 95% CI 0.71 - 1.07, Figure 1B). Five-year survival for patients undergoing adjuvant radiation was 40.4% (95% CI 30.2 - 50.3%) whereas 5-year survival for patients undergoing adjuvant chemotherapy was 25.9% (95% CI 21.0 - 31.1%). Download : Download high-res image (131KB) Download : Download full-size image Conclusions: Among women with stage II-III uterine LMS, use of chemotherapy is common and increasing while use of radiation therapy is decreasing. Radiation therapy is associated with improved survival while there was no association between use of adjuvant chemotherapy and survival. Prospective trials are needed to determine the optimal adjuvant therapy for women with stage II-III LMS.