Prognosis of uterine and extrauterine low-grade endometrial stromal sarcoma：an observational cohort study

Objective: Little is known about the survival differences between uterine and extrauterine low-grade endometrial stromal sarcoma (LGESS). Survival outcomes, consisting of disease-free survivals and overall survivals, were compared in these two entities. Methods: From February 2012 to June 2019, all primary LGESS cases and LGESS cases with first recurrence in the study center were reviewed. The clinicopathological characteristics and survival outcomes of extrauterine and uterine LGESS patients were compared for both primary and recurrent diseases. Results: During the study period, 143 patients with primary LGESS and 56 patients with recurrent LGESS were included and followed up to June 1, 2020, among whom 8 (5.6%) and 10 (17.8%) patients were identified as having extrauterine LGESS. Patients with primary and recurrent extrauterine LGESS had similar clinicopathological characteristics to those of patients with uterine LGESS. In primary or in recurrent LGESS cases, in univariate analysis, patients with uterine and extrauterine LGESS had similar disease-free intervals after the last treatment, and they also had similar overall survivals after the diagnosis. Ovarian preservation led to significantly increased recurrence for primary LGESS (hazard ratio [HR] 4.9, 95% confidence interval [95% CI] 2.3-10.1, P <0.001) and repeated recurrence for recurrent LGESS (HR 3.1, 95% CI 1.3-7.3, P =0.009). Surgical treatment for recurrent LGESS decreased repeated recurrence after the first recurrence (HR 0.2, 95% CI 0.1-0.7, P =0.006). No factors were found to be associated with the overall survival of primary or recurrent LGESS. Conclusion: The clinical characteristics and survival outcomes of extrauterine LGESS are similar to those of uterine LGESS. Surgery is the treatment of choice for recurrent LGESS. Ovarian preservation is detrimental to disease-free survival but not to overall survival in both uterine and extrauterine LGESS.