Serous component is a recurrence predictive factor of grade 1 endometrioid carcinoma at stage IA: A multi-institutional and retrospective study

Abstract

Background The incidence of grade 1 endometrioid carcinoma (EG1) at 2009 International Federation of Obstetrics and Gynecology (FIGO) stage IA was the highest in endometrial carcinoma. Several studies and guidelines classified EG1 into recurrent low risk and did not recommend patients received adjuvant therapy. However, not a few case with EG1 recurred. The aim of this study was to examine whether EG1 at 2009 FIGO stage IA with a less than 5% serous component resembling ovarian high- or low-grade serous carcinoma (SC) was a risk factor for recurrence or worse progression free survival (PFS). Methods Between 1990 and 2015, patients who received total abdominal hysterectomy and bilateral salpingo-oophorectomy for grade 1 endometrioid carcinoma at stage IA were enrolled at multiple centers. In addition to pathological review using 2014 World Health Organization (WHO) criteria, SC and several pathological features, including lympho-vascular invasion, were identified. A retrospective analysis to examine whether SC was a risk factor of recurrence was conducted. Results During the observational period, 236 patients were included in our study. Among them, SC was noted in 14 patients. Five patients showed recurrence and 4 of them had SC. Multivariate analysis for recurrence revealed that SC was an independent risk factor of recurrence (hazard ratio (HR) 139, p<0.001). PFS of patients with SC was worse than of patients without SC (p<0.001). Multivariate analysis for PFS demonstrated that SC was a significant prognostic factor (HR 98.9, p<0.0001). Conclusion SC was the strongest risk factor of recurrence for patients with EG1 at FIGO stage IA. Therefore, a new treatment strategy may be needed for patients with SC.