Introduction

Uterine sarcoma is a rare and aggressive heterogeneous malignant tumor originating from the mesodermal tissues (muscle and supportive tissues) [1]. It is characterized by nonspecific clinical presentations, high recurrence rates and poor prognosis, accounting for about 1% of female genital tract malignancies and 3–7% of uterine cancers [2]. The incidence of uterine sarcoma increases with age and is reported to be about 6.4 per 100,000 in women aged above 50 years in America [3].

According to the traditional histological classification, uterine sarcoma mainly included carcinosarcoma (CS), leiomyosarcoma (LMS), endometrial stromal sarcoma (ESS), undifferentiated sarcoma (UUS) and other less frequent histological subtypes, such as adenosarcoma. In 2009, the International Federation of Gynecology and Obstetrics (FIGO) revised the staging system and reclassified CS as endometrial cancer due to its similar dedifferentiated or metaplastic form to endometrial cancer [2]. The new uterine sarcoma classification mainly contains three pathological subtypes: LMS, ESS, adenosarcoma and undifferentiated endometrial sarcoma, of which LMS is the most common [4].

Diagnosis of uterine sarcoma is generally difficult before surgery because of nonspecific symptoms, such as irregular vaginal bleeding, abdominal or pelvic mass and pain, or even no symptom [4, 5]. Ultrasonography, magnetic resonance imaging, computed tomography and cancer antigen 125 (CA125) level are useful preoperative diagnostic methods. However, distinguishing uterine sarcoma from benign uterine lesions such as fibroids is difficult due to the lacking specific symptoms or diagnostic techniques, resulting in high misdiagnosis rates, which may lead to serious consequences [6, 7].

There is no standardized treatment for uterine sarcoma due to its rarity and heterogeneity. Early-stage uterine sarcoma is mainly treated by surgery according to different pathological types, including total hysterectomy with bilateral sal**o-oophorectomy (TH-BSO) [3, 17]. Our research presented is a comprehensive analysis of uterine sarcoma and examines 75 Chinese patients over a 10-year period using the latest classification system for more detailed results.

Our findings revealed that LMS had a poorer prognosis than that of ESS. Specifically, for the ESS group, we determined post-menopausal, high-grade and LVSI as key factors associated with reduced survival. Furthermore, the study highlighted the potential diagnostic value of CDFI, enabling it to distinguish between benign and malignant tumors and representing a new research topic.

CDFI provide a new direction for distinguishing uterine sarcoma from uterine fibroids. In our research, 62.9% of patients had CDFI during the examination. CDFI positive signals had a negative effect on survival of LMS group. This suggests the potentially important role of CDFI in the evaluation of the malignant transformation of uterus myoma, which is similar to a finding reported by Yang Hua [18]. Asim Kurjak reported that a cutoff in resistance index (RI) of 0.4 of tumoral blood vessels could distinguish uterine sarcoma from uterus myoma with a higher RI [19]. The diagnostic value of this cutoff is 90.91%, 99.82%, 71.43% and 99.96% in sensitivity, specificity, positive predictive value and negative predictive value, respectively [19]. However, the study had small sample sizes (n = 10). Sun et al. found that increased vascularity on color Doppler ultrasound could sometimes favor malignancy, especially when combined with a large size and degenerative cystic changes [20]. Further studies are needed to figure out the clinical significance of CDFI for uterine sarcoma.

Univariate analysis demonstrated that over 50 years, post-menopause, advanced stage and ≥ 1/2 myometrial invasion were significantly associated with poorer survival; while multivariable analysis identified that post-menopause and advanced stage were independent prognostic factors for survival of the total cohort and the LMS group. These findings were consistent with previous studies [14, 21,22,23]. Thus, they were not limited by race or traditional classification systems.

Studies showed that prognoses of different pathological types of uterine sarcoma varied a lot [24,25,26,27]. Our study showed that ESS had a significantly lower recurrence and a higher 5-year survival rate than LMS, and the survival of LG-ESS is prior to those of LMS and HG-ESS, which was in agreement with previous studies [28,29,30,31]. It’s reported that pathological subtype is a significant prognostic factor for OS [30]. However, pathological type isn’t a prognostic factor for survival in our study, which may be related to the merger of LG-ESS and HG-ESS into ESS because of small sample size. The proportion of FIGO I stage in the ESS group is higher than that in the LMS group (86.11% vs. 72.73%). Otherwise, misdiagnosis of LMS as uterine leiomyoma because of the same symptoms and delayed treatment due to minimally invasive therapy as well as inadvertent dissemination [32]. Alexandra Huss’s study reported that three cases LMS were diagnosed at tumor recurrence [30]. LG-ESS grew slowly and had a good prognosis in initial stages than that of HG-ESS in our study. Recently several studies have shown that chromosomal rearrangments and gene amplifications can provide new ideas for the diagnosis and treatment of HG-ESS [33, 34], However, our study lacks exploration on relevant molecular markers because of the earlier diagnosed patients.

Compared with previous studies, our investigation is distinctive in several aspects. (1) Geographical and racial backgrounds. Our study is based on certain Chinese patients in a way. It thus considerably complements the currently available literatures that focus on the clinicopathological features and prognosis of uterine sarcomas conducted in Western population. It significantly increases the global knowledge database regarding potential ethnic and geographic differences in sarcomas. (2) Utilization of the new classification system. This study uses the new classification of uterine sarcomas from 2014 in an attempt to provide an up-to-date exploration of their clinicopathological characteristics and prognosis. (3) Detailed subtype analysis. Given the evident heterogeneity within uterine sarcomas, subgroup analysis was performed separately and most survival factors were developed for each sarcoma group, namely ESS and LMS respectively. This is a valuable supplement that should be deserving of clinical attention because different pathological types of sarcomas present their exclusive influential factors and prognoses, which agents nation planning and judgement prognosis. (4) The usage of CDFI, as a potential malignant myoma indicator, offer an innovation that it may play an important role in novel non-invasive diagnostic techniques.

Our study had some limitations. First, the small sample sizes of adenosarcoma limits the statistical power and generalizability of the findings. This constraint makes it challenging to conduct comprehensive subgroup analyses or to conclude the prognostic implications for rare sarcoma types definitively. Second, the retrospective nature of the study design made it subject to selection and recall bias. These biases could affect accuracy of the collected data and interpretation of the study’s findings. Third, the study was performed in a single center. Its findings may not be broadly applicable to all populations. Forth, the study suggests CDFI as a potentially valuable tool for identifying malignant myomas, which is preliminary and requires further validation through larger, prospective studies to determine its clinical utility and accuracy.

Conclusion

According to our results, LMS is more aggressive than ESS. Post-menopause and advanced stage are independent risk factors of survival for the total patients and LMS, which were not limited to race or traditional classification system. Meanwhile, post-menopause, high-grade and LVSI are independently related to decreased survival in the ESS group. Uterine myoma with blood flow signal may be a useful indicator of malignant myoma, which needs to further validate its diagnostic utility in large-scale, multi-center studies and refine protocols for the management of uterine sarcomas.