Background: It has been reported that prognosis is less favorable in poorly (G3) differentiated endometrioid adenocarcinoma than in well (G1) or moderately (G2) differentiated endometrioid adenocarcinoma. The goal of this study is therefore to analyze the prognosis of G3 endometrioid adenocarcinoma and various factors that may predict a favorable prognosis. Method: This study included 699 Japanese cases of endometrioid adenocarcinoma at the International Federation of Gynaecology and Obstetrics (FIGO) surgical stages I-IV (including 74 G3 cases). We investigated the G1-G3 survival rates of endometrioid adenocarcinoma cases and the G2 and G3 disease-free periods. We also examined the clinicopathological characteristics of G3 endometrioid adenocarcinoma. Result: The prognosis was poor in stages III and IV in G3 and in G2 cases, but recurrence was observed more frequently in G3 cases than in G2 cases. Adnexal metastasis and high pre-surgery CA602 values showed significantly low P-values for survival. Conclusions: We suggest that the risk of late recurrence is higher in G3 than in G2 cases. The absence of adnexal metastasis and low pre-surgery CA19-9 values may suggest a relatively favorable prognosis in G3 endometrioid adenocarcinoma.
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