Long-Term Outcome and Failure Patterns in Early-Stage Endometrial Cancer After Postoperative Adjuvant Radiotherapy: A Multi-Institutional Analysis Update Data

Abstract

The aim of this study was to analyze survival outcomes and patterns of recurrence over time according to the radiotherapy mode in different risk groups and to provide reference for further optimization of treatment choices MATERIALS/METHODS: 1,298 stage I or Ⅱ EC patients receiving adjuvant radiotherapy from 13 centers in China were included between January 2000 to January 2017. The enrolled patients were categorized as low-risk (LR), intermediate-risk (IR), high-intermediate-risk (HIR) and high-risk groups (HR) according to ESMO-ESGO-ESTRO classification, while the radiotherapy modality consisted of the external beam radiotherapy (EBRT)and vaginal brachytherapy (VBT)alone. The key outcome of interest was the overall survival and time-dependent recurrence patterns. Disease-free interval (DFI) events were defined as time to first site recurrences, classifying as vaginal, regional (including intra-pelvic sites, or regional lymph nodes such as para-aortic lymph nodes) and distance metastasis. Competing risks regression analysis were applied to compare the time-to the first recurrence patterns according to the risk groups and radiotherapy modality. And hazard curves describe the change of failure rate over time.The median follow-up of 51 months. The 10-year overall survival rates of LR, IR, HIR, and HR were 90 %,85%,84% and 83%, respectively (P = 0.018). In all, 91 of 1,298 patients developed recurrences including 8 vaginal relapses, 17 regional recurrences and 66 distant metastases. And the 5-year disease-free survival rates were 96%, 92.8%, 89% and 85% for the four risk groups, respectively (P < 0.001). In competing risks regression analysis, after adjusting for other prognostic factors, the distribution of recurrence preferences differed between risk groups and radiotherapy modalities. The 10-year cumulative incidence of distant recurrence was the highest with HR group (11.9%), followed by HIR (6.68%), IR (4.65%) and LR (2.00%) group (Gray's test, P < 0.001). There was also a trend toward higher rates of regional relapse in HR (2.18%) and HIR group patients (2.76%) than the IR (1.3%) or LR (1.43%) group of patients, but this was of no statistical significance (Gray's test, P > 0.1). For the subgroup analysis, the patients received EBRT in the HIR and HR group had higher 10-year rate of distant metastasis than the VBT alone (Gray's test, P = 0.004). And the EBRT group had a tendency of lower incidence of locoregional recurrence (1.66% vs 3.54% for VBT, Gray's test, P = 0.105).This study demonstrated the differential susceptibility to distant metastasis based on the risk classification and radiotherapy modality. Defining different patterns of EC recurrence over time in details can improve EC care through surveillance guidelines and can guide the design of clinical studies.K. Ren: None. L. Zou: None. T. Wang: None. X. Li: None. H. Zhu: None. S. Sun: None. M. Jin: None. F. Zhang: None. X. Hou: None. L. Wei: None. K. Hu: None.