Objective: The aim of this study was to determine the rates of local control and survival after relapse in patients with stage I endometrial cancer treated in the multicenter randomized PORTEC trial.
Methods: The PORTEC trial included 715 patients with stage 1 endometrial cancer, either grade 1 or 2 with deep (>50%) myometrial invasion or grade 2 or 3 with <50% invasion. In all cases an abdominal hysterectomy was performed, without lymphadenectomy. After surgery, patients were randomized to receive pelvic RT (46 Gy) or no further treatment.
Results: The analysis was done by intention-to-treat. A total of 714 patients were evaluated. At a median follow-up of 73 months, 8-year actuarial locoregional recurrence rates were 4% in the RT group and 15% in the control group (P < 0.0001). The 8-year actuarial overall survival rates were 71 (RT group) and 77% (control group, P = 0.18). Eight-year rates of distant metastases were 10 and 6% (P = 0.20). The majority of the locoregional relapses were located in the vagina, mainly in the vaginal vault. Of the 39 patients with isolated vaginal relapse, 35 (87%) were treated with curative intent, usually with external RT and brachytherapy, and surgery in some. A complete remission (CR) was obtained in 31 of the 35 patients (89%), and 24 patients (77%) were still in CR after further follow-up. Five patients subsequently developed distant metastases, and 2 had a second vaginal recurrence. The 3-year survival after first relapse was 51% for patients in the control group and 19% in the RT group (P = 0.004). The 3-year survival after vaginal relapse was 73%, in contrast to 8 and 14% after pelvic and distant relapse (P < 0.001). At 5 years, the survival after vaginal relapse was 65% in the control group compared to 43% in the RT group.
Conclusion: Survival after relapse was significantly better in the patient group without previous RT. Treatment for vaginal relapse was effective, with 89% CR and 65% 5-year survival in the control group, while there was no difference in survival between patients with pelvic relapse and those with distant metastases. As pelvic RT was shown to improve locoregional control significantly, but without a survival benefit, its use should be limited to those patients at sufficiently high risk (15% or over) for recurrence in order to maximize local control and relapse-free survival.