In 1983, Bockman classified EC into type I EC (estrogen-dependent) and type II non-EC (non-estrogen-dependent)[17]. Type I EC, which is more common in perimenopausal and premenopausal women, presents with irregular vaginal bleeding as the main symptom, while type II is more common in the postmenopausal stage, with postmenopausal drainage and vaginal bleeding as the main symptoms. In clinical practice, more than 70% of EC are type I EC (estrogen-dependent)[18]. Therefore, this study mainly focused on type I EC. In recent years, Based on genomic analysis, EC can be divided into four different categories[19]: polymerase epsilon ultramutated, microsatellite unstable, copy number high/'serous-like' and copy number low/microsatellite stable. These subtypes have an important impact on prognosis, especially in the identification of endometrial patients with risk of recurrence [19–20]. However, this classification method is costly and technically demanding, which limits its clinical application. This study is a retrospective study, so all 192 specimens were classified by traditional Bockman classified EC.
Atypical hyperplasia (AH) is a precancerous lesion of the endometrium with a 40% risk of final pathological diagnosis of EC at the time of hysterectomy [21]. Preoperative staging curettage and pathological biopsy are the gold standard for EC diagnosis, but there is a certain rate of missed diagnosis, and some patients can only be definitively diagnosed after hysterectomy. In this study, 8 cases of AH and 38 cases of AHCE were diagnosed as EC in FS, which was consistent with PS, and higher than that reported in the literature. This is because this study was a retrospective study. Including all patients diagnosed with EC was first, then their intraoperative frozen and preoperative staged curettage biopsy were traced back to test for consistency with PS.
For EC, the judgment of the depth of MI and tumor grade on intraoperative FS is an independent risk predictor for lymph node metastasis in EC [22–23]. Therefore, whether the results of FS (the depth of MI and grade) might be helpful for an intraoperative decision of performing lymphadenectomy in patients with early-stage EC depends on whether FS could accurately reflect the pathologic results of the final PS and needs to be further explored. There are some contradictory reports about the accuracy and reliability of the results of FS and PS in EC [24–26]. In this study, the results of 292 clinical cases showed that compared with postoperative PS, FS had a higher predictive value in the depth of MI; it showed higher sensitivity (94.96%), specificity (64.81%), higher consistency with the depth of postoperative MI (< 50% (94.96% ) and ≥ 50% ( 64.81%)), thus suggesting that FS could be a guiding method for lymph node dissection in early EC. Moreover, the consistency of FS and PS in MI and tissue grading is higher than the published literature [27]. Therefore, FS had a high guiding value for the operation of EC in regard to MI and tumor grade.
Sentinel lymph node (SLN) is defined as the first batch lymph node, which can be passed by the lymphatic metastasis of the primary carcinoma through the regional lymphatic drainage pathway. SLN biopsy, as an important mean of surgical treatment of EC, has unique advantages in avoiding over treatment or insufficient surgical scope; however, its clinical application is still controversial[28–30]. This study is a retrospective study of EC cases who underwent surgery in our hospital from 2015 to 2019.We performed abdominal and pelvic lymph node dissection, including sentinel lymph node dissection. Unfortunately, we did not label SLNs separately.
In recent years, minimally invasive techniques have played an increasingly important role in the treatment of gynecological diseases. Laparoscopic surgery has the advantages of clear vision, precise operation, low intraoperative blood loss[31] and short hospital stay. It has been used as the preferred surgical method for early EC and is widely used worldwide. Although the intrauterine device was used in laparoscopic surgery, the effect of intraoperative freezing on the depth of EC myometrial invasion was not affected[32].Large prospective studies have shown that laparoscopic and laparotomy have similar outcomes in terms of tumor-free progression and overall survival in EC patients[33–34]. This suggests that laparoscopic surgery has more advantageous in early EC surgery.
In summary, our results are consistent with other similar reports[35–37]. FS has a high predictive value for the depth of MI, which suggests that FS can be a reliable diagnostic value for determining the depth of MI in EC surgery to guide surgical treatment, so as to avoid adverse outcomes and adverse effects caused by over- or under-treatment in early EC patients.
The study also has some limitations. The study had some limitations. First, this was a relatively small retrospective study. Second, patients with type II endometrial adenocarcinoma were not included in the analysis. However, the research institution is the General Hospital of Ningxia Medical University, which is a third class a hospital with greater influence in Ningxia and even the northwest region. Therefore, the involvement of experienced professional gynecological pathologists in FS and PS assessment was an advantage of this study.