Uterine papillary serous and clear cell carcinomas: Comparison of characteristics and clinical outcomes.

INTRODUCTION: To assess the rate of disease control and survival after adjuvant treatment in patients with uterine papillary serous (PSC) and clear cell carcinoma (CCC) and compare the results between these two subtypes. METHODS: The medical charts of 199 patients with de novo uterine PSC or CCC who underwent radiotherapy (RT) following surgery between 2001 and 2019 in three radiation oncology departments were retrospectively evaluated. Adjuvant treatment was decided by a multidisciplinary tumor board. All patients were planned to undergo adjuvant 4-6 cycles of chemotherapy with external beam RT (EBRT) and/or vaginal brachytherapy (VBT). RESULTS: Median age was 63 years for all, 64 years for PSC, and 59 years for CCC, respectively. Complete surgical staging was applied in 98% of patients. Histopathologic subtype was PSC in 142 (71%) and pure CCC in 57 (29%) patients, respectively. FIGO stage was I in 107 (54%), II in 35 (18%), and III in 57 (28%) patients, respectively. Lympho-vascular space invasion and positive peritoneal cytology (PPC) were present in 42% and 10% of patients, respectively. All patients but 23 (12%) underwent adjuvant chemotherapy. Median follow-up was 49.5 months for all patients, 43.9 months for patients with PSC, and 90.4 months for patients with CCC, respectively. During follow-up, 20 (10%) patients developed pelvic recurrence (PR) and 37 (19%) developed distant metastasis (DM). PSC subtype increased the PR and DM rates, although the latter not statistically significant. The 5-year overall survival and disease-free survival rate was 73% and 69% for all patients, 71% and 66% for patients with PSC, and 77% and 75% for patients with CCC, respectively. The difference was more prominent in patients with stage ≥ IB disease. In multivariate analysis, advanced age and PPC significantly decreased all survival rates. CONCLUSION: PSC has a worse prognosis than CCC with regard to pelvic and distant recurrence with a trend for decreased survival rates. Therefore, a more aggressive therapy is needed for patients with uterine PSC, particularly in patients with stage ≥ IB disease.