While total surgical resection remains the preferred course of action for EC, 65–85% of patients experience recurrence after surgery (18). In recent years, with advances in detection and treatment technology, the recurrence rate has decreased (19). Approximately 70% of patients with EC have been reported to have stage I disease, with a 5-year OS rate ranging from 74–91%. However, the 5-year OS rate has been reported as 57–66% for stage III and only 20–26% for stage IV, suggesting that metastasis is associated with a poorer outcome (20, 21). The prognostic heterogeneity following EC surgery varies greatly by tumor stage (22). Accurate prognosis following surgery for EC is essential to inform patients accurately of their long-term prognosis and to select patients for adjuvant therapy. Although the FIGO staging system is currently the most commonly used staging system, the reported prognostic factors vary, and the best way to stratify the risk of EC patients is unknown (23). Herein, two nomograms were created to predict RFS and OS in individuals following EC resection, based on patient-related factors. This information makes it possible to decide on what individualized treatments and monitoring methods to pursue and to determine a patient's prognosis. It is important to note that the nomograms created herein were constructed using information obtained from nearly a decade's worth of record of patients with EC who underwent surgery. Moreover, unlike the previously suggested nomograms based on the Surveillance, Epidemiology, and End Results program database (11), the effectiveness of the current nomograms has been thoroughly evaluated and internally validated. In addition, the present study included several variables mentioned previously that affect prognoses (24–26). Various factors have been identified to be associated with outcomes, with little agreement on which factors determine prognosis (10, 26). For example, some studies (10, 27, 28) have reported age, tumor stage, grade, LVSI, myometrial invasion, cervical stromal invasion, and tumor size. However, other researchers found no link between long-term survival and LVSI, histological type, menopause, and adenomyosis (29–32). Similarly, we found no association between menopause, adenomyosis, and RFS or OS in the current study (Tables 1 and 2). Comparatively, several studies on EC have revealed that LVSI, advanced FIGO stage (III/IV), histologic grade, myometrial invasion depth, cervical stromal invasion, and tumor size at diagnosis are associated with poorer outcomes (8, 27, 28, 33, 34). In the present study, patients with an AACCI score > 2 and primary tumor diameter > 2 cm had 93-fold and 6-fold higher mortality risks, respectively, and patients with an AACCI score > 2, stage IV disease, and high histologic grade had 52-fold, 138-fold, and 3-fold higher risks of recurrence, respectively. AACCI score was an independent risk variable for OS and RFS, consistent with previous conclusions (35).
The prognosis for patients with tumors such as EC can be heterogeneous, making accurate risk stratification of these patients important. The nomograms may provide more individualized prognostic information to patients rather than the FIGO staging system, which is determined using data from the population. Li et al. (11)suggested a nomogram for patients with EC that considered age, FIGO stage, histologic grade, histologic type, distant metastasis, and tumor stage in the model, and we consider this model to lack convenience and practicality. Hence, we limited our model factors to patients undergoing surgical treatment for EC. Nomograms stratified by cutoffs helped identify distinct groups of patients with different relapse and mortality risks (Fig. 2). Moreover, both nomograms showed good discriminatory capability, with C-statistics of 0.895 for predicting RFS and 0.891 for predicting OS (Fig. 1). The nomograms also made median 5-year survival predictions, similar to those of the Kaplan-Meier curve survival. Taken together, these data suggest that the proposed nomograms can offer patients with postoperative EC information on the risk of recurrence and survival. Compared with previous models (36), the IDI evaluated the overall improvement of the model: 0.189 for 5-year and 0.173 for 10-year RFS prediction.
This study has several limitations. First, this was a single-institution retrospective study. Patient differences will affect the universality and prediction accuracy of the model. Second, the prognostic significance of OS was not entirely accurate because data that may affect patient survival, such as chemotherapy, radiotherapy, and surgery, were excluded from the nomogram. Moreover, next generation sequencing molecular classification has demonstrated superiority over conventional pathological assessment of grade and histotype (37). Future modeling should consider these factors. Finally, although the proposed nomograms were internally validated using bootstrapping, additional studies are required for external validation.
In conclusion, this study is the first to develop online nomograms based on three variables to predict RFS and OS dynamically in women with EC. The proposed nomograms can be used to stratify patients into different predictive groups based on relapse and long-term outcomes. Clinicians can use our model through the web calculator we created. Additionally, the nomograms performed well when internally validated. To demonstrate their usefulness in assessing long-term prognosis following therapeutic EC excision, external validation of the proposed nomograms is required.