The comparison of pure uterine serous carcinoma and mixed tumor with serous component: a single-institution review of 91 cases

Background Pure uterine serous carcinoma (p-USC) and mixed tumors with serous component (m-USC) are aggressive subtypes of endometrial cancer associated with high mortality rates. This retrospective study aimed to compare clinicopathologic features and outcomes of p-USC and m-USC in a single center. Methods This study retrospectively reviewed patients diagnosed with USC at Peking University People’s Hospital between 2008 and 2022. T-tests and chi-square tests were used to compare clinicopathological characteristics between p-USC and m-USC. Kaplan-Meier survival curve and Cox regression analysis were used to analyze the impact of clinical and pathological variables on OS and PFS. Results Among the 91 patients who underwent surgery, 65.9% ( n = 60) were p-USC, and 34.1% ( n = 31) were m-USC. Patients with p-USC had earlier menopause ( P = 0.0217), a lower rate of progesterone receptor(PR) expression ( P < 0.001), and were more likely to have positive peritoneal cytology ( P = 0.0464). After a median follow-up time of 40 months, 28 (46.7%) p-USC and 9 (29%) m-USC patients had progression disease, 18 (30%) and 8 (25.8%) patients died of their disease. 5-year PFSR were 51.2% and 75.3%, respectively, and 5-year OS rates were 66% and 67.4%. Kaplan-Meier survival analysis showed that p-USC was more likely to relapse than m-USC ( P = 0.034), but there was no significant difference in OS. Cox regression analysis showed that lymph node metastasis and surgical approach were risk factors for OS, and myoinvasion depth ≥ 1/2 was an independent risk factor for PFS. Conclusions p-USC was more likely to relapse than m-USC, but there was no significant difference in OS between the two subtypes.