The Prognostic Value of Tumor Cell Clusters in the Fallopian Tube Lumen in Stage I Endometrioid Carcinoma

The aim of this study was to investigate the pathologic prognostic factors such as tumor cell clusters (TCCs) in the fallopian tube lumen, myometrial invasion patterns, and positive peritoneal cytology (PPC) in women with Stage I endometrial endometrioid carcinoma (EEC). From 2009 to 2020, consecutive patients with Stage I EEC who underwent hysterectomy and bilateral salpingectomy were included. The primary outcome was the recurrence-free survival (RFS) rate, and the clinicopathological factors affecting RFS were analyzed. A total of 765 patients were enrolled. Seventeen patients (2.2%) had TCC in the fallopian tube lumen, and 58 patients showed a microcystic elongated and fragmented pattern (7.6%). PPC was found in 19 patients (2.5%). The median follow-up period was 61.0 months (range: 2.0–149.7). The majority (88.6%) of patients had Stage IA EEC. The 5-year RFS and overall survival rates were 97.5% and 98.5%, respectively. In multivariate analysis for RFS, the significant prognostic factors were lymphovascular invasion (hazard ratio = 4.604; 95% CI: 1.387–15.288; P = 0.013) and grade (grade 2; hazard ratio = 4.949; 95% CI: 1.035–23.654; P = 0.045, and grade 3; hazard ratio = 5.469; 95% CI: 1.435–20.848; P = 0.013). Other pathologic factors including TCC in the fallopian tube lumen, myometrial invasion patterns, PPC, and hormonal status had no prognostic significance. TCC in the fallopian tube lumen, myometrial invasion pattern, PPC, and estrogen and progesterone receptor positivity were not significant prognostic factors in Stage I EEC. In contrast, lymphovascular invasion and grade were significant prognostic factors.