Impact of adjuvant treatment and prognostic factors in stage I uterine leiomyosarcoma patients treated in Commission on Cancer®-accredited facilities.

Objectives: Determine the impact of adjuvant chemotherapy (ACT) and prognostic factors in surgically managed patients with stage I uterine leiomyosarcoma (ULMS).

Methods: Women who underwent hysterectomy and were diagnosed with stage I ULMS between 2010 and 2014 in the National Cancer Database were eligible for this observation study. Inverse probability of treatment weighting based on propensity score was used to balance clinical characteristics between ACT and no ACT patients. Hazard ratio (HR) and 95% confidence interval (CI) were estimated from Cox modeling.

Results: There were 1059 eligible patients with stage I ULMS including 514 treated with ACT and 545 with no ACT. Patient characteristics and tumor features varied in patients treated with ACT vs. no ACT (P < .0001). Multivariate survival analysis demonstrated that patient age, comorbidity score, tumor size, lymphovascular space invasion (LVSI) and grade were independent prognostic factors. After propensity score weighting to control for imbalance of prognostic clinical factors, adjusted five-year survival was 61.7% vs. 61.3% and restricted mean survival time was 39.7 vs. 40.6 months for ACT vs. no ACT, respectively. Risk of death in a weighted Cox analysis of overall survival was similar (HR = 1.08, 95% CI = 0.85-1.37, P = .054) for ACT vs. no ACT patients. Subset analysis demonstrated that survival was similar in ACT vs. no ACT patients categorized by age, tumor size and LVSI or with high grade or ungraded tumors. In contrast, patients with low grade tumors had worse 5-year survival (82.3% vs. 91.5%) and an increased risk of death (HR = 3.79, 95% CI = 1.15-12.40, P = .028) following ACT vs. no ACT.

Conclusions: ACT did not improve survival over no ACT in patients with stage I ULMS and was inferior in patients with low grade tumors.