Purpose: This follow-up of a randomized study was conducted to assess the long-term effects of external beam radiation therapy (EBRT) in the adjuvant treatment of early-stage endometrial cancer.
Patients and methods: Between 1968 and 1974, 568 patients with stage I endometrial cancer were included. After primary surgery, patients were randomly assigned to either vaginal radium brachytherapy followed by EBRT (n = 288) or brachytherapy alone (n = 280). Overall survival was analyzed by using the Kaplan-Meier method. A Cox proportional hazards model was used to estimate hazard ratios (HRs) with 95% CIs. We also conducted analyses stratified by age groups.
Results: After median 20.5 years (range, 0 to 43.4 years) of follow-up, no statistically significant difference was revealed in overall survival (P = .186) between treatment groups. However, women younger than age 60 years had significantly higher mortality rates after EBRT (HR, 1.36; 95% CI, 1.06 to 1.76) than the control group. The risk of secondary cancer increased after EBRT, especially in women younger than age 60 years (HR, 2.02; 95% CI, 1.30 to 3.15).
Conclusion: We observed no survival benefit of external pelvic radiation in early-stage endometrial carcinoma. In women younger than age 60 years, pelvic radiation decreased survival and increased the risk of secondary cancer. Adjuvant EBRT should be used with caution, especially in women with a long life expectancy.