A retrospective study for investigating the outcomes of endometrial cancer treated with radiotherapy

Objective: To clarify the role of radiotherapy for endometrial cancer. Methods: Data were analyzed for 39 247 patients with endometrial cancer registered with the Gynecologic Cancer Registry of the Japan Society of Obstetrics and Gynecology from 2004 to 2011. Results: The rates of 5-year overall survival (5y-OS) in the radiotherapy and surgery groups were 53.6% and 94.5% in stage I or II, and 15.5% and 67.5% in stage III or IV, respectively. The prognosis in the radiotherapy group was significantly poorer than that in the surgery group. In multivariate analysis, age, advanced stage, histological type, risk of recurrence, and initial radiotherapy were independent prognostic factors. The rates of 5y-OS with no adjuvant therapy, adjuvant chemotherapy, and adjuvant radiotherapy were 95.3%, 92.9%, and 87.1% for stage I or II, respectively, with significant differences among all groups (P < 0.001), and 60.0%, 70.4%, and 55.5% for stage III or IV, respectively, with significant differences of adjuvant chemotherapy with no adjuvant therapy (P < 0.001) and with adjuvant radiotherapy (P < 0.001). In multivariate analysis, age, advanced stage, histological type, lymphadenectomy, and adjuvant radiotherapy were independent prognostic factors. Conclusion: Patients treated with radiotherapy had a significantly poorer prognosis and the appropriate indication of radiotherapy for endometrial cancer requires further study.