The impact of combined radiation and chemotherapy on outcome in uterine papillary serous carcinoma compared to chemotherapy alone

OBJECTIVE: To investigate the impact of pelvic radiation on survival in patients with uterine serous carcinoma (USC) who received adjuvant chemotherapy. METHODS: Patients with stage I-IV USC were identified from the Surveillance, Epidemiology, and End Results program 2000 to 2009. Patients were included if treated with surgery and chemotherapy. Patients were divided into two groups: those who received chemotherapy and pelvic radiation therapy (CT_RT) and those who received chemotherapy only (CT). Kaplan-Meier curves and Cox regression proportional hazard models were used. RESULTS: Of the 1,838 included patients, 1,272 (69%) were CT and 566 (31%) were CT_RT. Adjuvant radiation was associated with significant improvement in overall survival (OS; p<0.001) and disease-specific survival (DSS; p<0.001) for entire cohort. These findings were consistent for the impact of radiation on OS (p<0.001) and DSS (p<0.001) in advanced stage (III-IV) disease but not for early stage (I–II) disease (p=0.21 for OS and p=0.82 for DSS). In multivariable analysis adjusting for age, stage, race and extent of lymphadenectomy, adjuvant radiation was a significant predictor of OS and DSS for entire cohort (p=0.003 and p=0.05) and in subset of patients with stage III (p=0.02 and p=0.07) but not for patients with stage I (p=0.59 and p=0.49), II (p=0.83 and p=0.82), and IV USC (p=0.50 and p=0.96). Other predictors were stage, positive cytology, African American race and extent of lymphadenectomy. CONCLUSION: In USC patients who received adjuvant chemotherapy, adjuvant radiation was associated with significantly improved outcome in stage III disease but not for other stages. Positive cytology, extent of lymphadenectomy and African race were significant predictors of outcome.