Poor prognosis of uterine serous carcinoma compared with grade 3 endometrioid carcinoma in early stage patients

Difference in prognosis between grade 3 endometrioid carcinoma (G3EC) of the endometrium and uterine serous carcinoma (USC) is controversial. In this study, we further evaluated the difference in prognosis, if any, between G3EC (n = 61) and USC (n = 47) on a total of 565 patients with endometrial cancer. In addition, meta-analysis was performed using data from seven previous publications (n = 8,637) and from the Asan Medical Center (n = 108). Regarding the cases from our institution, USC tended to occur in older patients (≥65 years) than G3EC (P = 0.011). Deep myometrial invasion (more than or equal to half) was more frequently identified in G3EC (36/61, 59.0 %) than in USC (17/47, 36.2 %) (P = 0.021). Between patients with early stage G3EC and USC (stages I and II), there were no significant differences in any clinicopathological parameter, but there was a significant difference in overall survival (P = 0.017) that was not found in advanced stage (P = 0.588). USC was an independent prognostic factor for poor overall survival (hazard ratio, 6.125; P = 0.030) in early stage patients. In the meta-analysis on 5-year survival in patients with early stage cancers, which also included our study results, a higher relative risk (1.92, 95 % CI 1.62–2.27) was demonstrated in USC than in G3EC (P