Utilization and outcomes of adjuvant therapy for stage II and III uterine leiomyosarcoma.

Objectives: The optimal adjuvant therapy for uterine leiomyosarcoma (uLMS) remains uncertain. We analyzed the utilization of adjuvant chemotherapy and radiation therapy for stage II and III uLMS and explored the association between use of adjuvant therapy and survival.
Methods: Patients with stage II or III uLMS treated from 2004 to 2016 and recorded in the National Cancer Database 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, and the receipt of radiation therapy was adjusted in the outcome model. 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.
Results: A total of 890 patients were identified. Adjuvant chemotherapy use increased from 62.2% in 2010 to 70.4% in 2016, whereas radiation usage decreased from 26.7% in 2010 to 10.4% in 2016. Patients with stage III (vs. stage II) disease were less likely to receive radiation therapy. After propensity score weighting, chemotherapy was associated with a 30% decreased risk of all-cause mortality in stage III patients (HR 0.70, 95% CI 0.45-0.98) but had no effect on mortality for stage II patients (HR 0.93, 95% CI 0.70-1.20). Radiation therapy was associated with a 26% decreased risk of mortality for stage II tumors (HR 0.74; 95% CI, 0.53-0.99) and a 57% decrease in mortality for stage III disease (HR 0.43, 95% CI 0.18-0.99).
Conclusions: Among women with stage II-III uLMS, use of chemotherapy is increasing while use of radiation therapy is decreasing. Radiation therapy is associated with improved survival in both stage II and III disease, while there was no association between use of adjuvant chemotherapy and survival in stage II patients.
Competing Interests: Declaration of Competing Interest Dr. Wright has received royalties from UpToDate and received research funding from Merck. Dr. Hou has served as a consultant for Foundation Medicine and Natera.
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