Analysis of the relapse patterns and risk factors of endometrial cancer following postoperative adjuvant chemotherapy in a phase III randomized clinical trial

Objective: This study was to analyze patterns and risk factors of relapse after postoperative adjuvant chemotherapy for endometrial cancer. Methods: Among patients enrolled in a randomized phase III trial (JGOG2043) investigating the efficacy of adjuvant chemotherapy for endometrial cancer at a high risk of progression, the recurrent patients were studied. Clinical information were collected, and correlation between relapse-related factors and clinicopathological factors were analyzed. Results: Among 193 patients analyzed, 50% had local relapse and 63% had distant relapse. Local relapse involved regional lymph nodes in 30%, while distant relapse involved the abdominal cavity in 42%. Imaging was used to confirm relapse in 83%, and the median disease-free interval (DFI) was 11.5 months. Factors showing a significant correlation with DFI ≤12 months were residual tumor at surgery (p < 0.01), Grade 3 histology (p < 0.01), and lymph node metastasis (p = 0.03). In contrast, treatment with paclitaxel and carboplatin showed a significant correlation with DFI >12 months (p = 0.04). The median post-relapse overall survival (RS) was 23.9 months. In multivariate analysis, CA125 ≥ 100 U/mL prior to relapse (p < 0.01), distant metastasis (p < 0.01), DFI ≤ 12 months (p = 0.02), and not performing para-aortic lymphadenectomy (p = 0.01) were independently related to poor RS. Conclusions: Relapse of endometrial cancer following adjuvant chemotherapy often occurs by 1 year after treatment, with common relapse sites of the abdominal cavity and regional lymph nodes. Among treatment-related factors, RS was correlated with DFI and para-aortic lymphadenectomy.