Clinical research with large samples of uterine sarcoma in a single institution is challenging due to its low incidence and high malignancy. Moreover, the preoperative diagnosis of uterine sarcoma is difficult, and it is often misdiagnosed as uterine leiomyoma, which is often diagnosed during postoperative pathological examination (7). Most patients have no specific signs, and up to 25% of patients are asymptomatic (8). Although the use of magnetic resonance imaging (MRI) in the evaluation of malignancies is crucial, the cost of this imaging modality prevents it from becoming a routine preoperative examination tool (9). A study reported that ULMS occurred in 0.25 percent (1:400 patients) and unexpectedly in 0.12% (1:865) (10). Because uterine sarcomas arise in the deep muscle layers of the uterus, preoperative endometrial sampling is not easy to detect. For instance, a multicenter retrospective study of 302 patients found that 65% of cases were diagnosed as uterine sarcoma before surgery, and only 25% after endometrial sampling (11).
In current study, ULMS had the same incidence as ESS and 3-year survival rate of ULMS and ESS was 72.5%, and 77.5%, respectively. However, A retrospective analysis of 114 uterine sarcoma patients in western China showed that ESS cases (65.3%) were greater than LMS cases (29.8%) (12) and the 3-year survival rate of uterine sarcoma was 65.1% (13). This study's results are slightly higher than those reported in the literature, possibly because the number of patients was small and most of them were early-stage patients. Additionally, laparoscopy and laparotomy are surgical options, and some patients choose hysteroscopy because of submucosal fibroids. Minimally invasive technology has gradually increased the use of rotary cutters. FDA (Food and Drug Administration) issued a recommendation to limit the use of power pulverizers in 2014, and in the 2020 update, it was prohibited in principle. Doctors need to understand the risk of malignant intraperitoneal dissemination (14). The standard surgical procedure for uterine sarcoma is a total hysterectomy + double adnexectomy. Generally, systematic pelvic and para-aortic lymph node dissection is not routinely performed. Exploration should be performed during the operation, and enlarged or suspicious lymph nodes should be resected (15–17). Nasioudis et al., recently published a report showing the role of lymphadenectomy in early-stage uterine sarcomas. The report found that lymphadenectomy was not associated with better survival for patients with adenosarcoma, or low-grade ESS (after controlling for confounders). While patients with high-grade endometrial stromal/undifferentiated sarcoma who underwent lymphadenectomy had better survival. However, patients with leiomyosarcoma who underwent lymphadenectomy had a poorer survival (18). It is still controversial whether the ovaries should be preserved in patients with uterine sarcoma. Studies have shown that the recurrence rate of ovarian preservation in patients with lower-grade ESS is extremely high. Therefore, double adnexectomy is recommended, and postoperative estrogen replacement therapy is not advocated. However, some scholars have suggested that ovarian preservation can be considered for ESS patients of stage I after strict selection, and more evidence is needed to confirm this (19–21).
According to current study, menopausal status, tumor stage, pathological tumor size, lymph node resection, K i-67 expression, and PR expression in ULMS were associated with prognosis, but surgical stage and tumor size were independent risk factors. Similarly, there was an association between tumor size, tumor stage and prognosis in ESS, and menopausal status was an independent risk factor. Like our study, many studies have shown that the later the clinical stage of a tumor, the poorer the prognosis will be (22). Many studies have shown that PR is highly expressed in patients with uterine sarcoma and is associated with a favorable prognosis and improved overall survival. There are a few possible explanations for why PR receptor negativity is a negative prognostic factor in leiomyosarcoma. For example, PRs are involved in the cell cycle, and PR negativity may lead to uncontrolled cell growth. Additionally, PRs are involved in the production of proteins that promote angiogenesis and suppress the immune system. Therefore, PR negativity may limit the ability of tumors to grow and make them more susceptible to immune attack. Overall, the evidence suggests that PR receptor negativity is a negative prognostic factor in leiomyosarcoma. Patients with PR-negative tumors are more likely to have a shorter survival time than patients with PR-positive tumors (23, 24).
Tumor size is a significant prognostic factor in uterine sarcomas. D’Angelo et al., examined the impact of clinicopathological findings in ULMS on survival outcomes(25). They proposed that larger tumors (e.g. >10cm) have a poorer prognosis. Another study concluded that mitotic count is an independent prognostic factor for uterine sarcomas (26). Tumor stage is also a crucial prognostic factor in uterine sarcoma. The 5-year overall survival rate of patients with stage I (50–55%) is higher than that of patients with stage II-IV (8–12%). (1). Similarly, Li et al also observed a significant correlation between tumor stage and overall survival in both univariate and multivariate analyses. The 3-year overall survival rate for all histological types was 75.4% for stage I, 57.1% for stage II, 33.3% for stage III, and 7.1% for stage IV (27). This study also shows that tumor stage and tumor size are associated with prognosis across pathological types, a finding that is consistent with literature. In addition, the prognosis of uterine sarcoma is also influenced by factors such as menopausal status, sarcoma overgrowth, lymphovascular space invasion, resection margin, depth of myometrial invasion, and mitotic figures (28–31). High-grade ESS and undifferentiated uterine sarcomas that are treated with adjuvant chemotherapy are likely to have better disease-free survival rates (32). According to a meta-analysis of hormone therapy in 315 cases of low-grade ESS, hormone therapy reduced the recurrence risk for stage I patients(33). Similarly, another retrospective cohort study revealed that hormone therapy reduces recurrence in stage II-IV low-grade ESS (34). Since 2014, UUS has no longer been classified as ESS, and the histology of some ESS in this study did not clearly mark weather LGESS or HGESS. Therefore, this study only conducted statistical analysis on whether it is LGESS.
Ki-67 was significantly expressed in leiomyosarcoma tissue compared to leiomyoma patients. Therefore, the combination of Ki-67 detection can be used in differential diagnosis of uterine sarcoma (35). A study showed that a Ki-67 index cut-off value of 35% was the most reliable indicator for predicting recurrent ESS. Therefore, the Ki-67 index may be a significant indicator of ESS prognosis (36). In this study, ULMS patients with Ki-67 expression ≤ 10% had a better prognosis. However, a small sample size and a short follow-up time were used in this study. Therefore, more studies with a larger sample size and multi-center trials are still needed in the future. This institution is a specialized hospital for obstetrics and gynecology and does not have the conditions for radiotherapy. Therefore, it is difficult to collect data on radiotherapy patients. Another limitation of the study is that it lacks residual tumor data. We were unable to obtain residual tumor data for most of our patients because they were at an early stage after surgery. Moreover, studies have shown that elevated serum LDH levels are common in patients with multiple malignant tumors, including ESS. LDH type A and LDH type D are specifically expressed in uterine sarcoma. The expression of LDH and its subtypes in serum can be a useful biomarker for the preoperative diagnosis of ESS (37, 38). However, our study is a recent project, and we were not able to collect a full 10 years of patient data. This is a limitation of our study, but we believe that the results are still clinically significant. We have included this paragraph in the discussion. For the impact of treatment methods on prognosis of uterine sarcoma, a larger sample size and longer follow-up are still needed in the future.