Outcome of high-risk stage IC, grade 3, compared with stage I endometrial carcinoma patients: the Postoperative Radiation Therapy in Endometrial Carcinoma Trial.

Purpose: Stage IC, grade 3 endometrial cancer is regarded as a high-risk category. Stage IC, grade 3 patients were not eligible for the randomized Postoperative Radiation Therapy in Endometrial Carcinoma (PORTEC) trial, but were registered and received postoperative radiotherapy.
Patients and Methods: The PORTEC trial included 715 patients with stage IC, grade 1 or 2, and stage IB, grade 2 or 3 endometrial cancer. Patients were randomly assigned after surgery to receive pelvic radiotherapy (RT) or no further treatment. A total of 104 patients with stage IC, grade 3 endometrial cancer were registered, of whom 99 could be evaluated. Patterns of relapse and survival were compared with PORTEC patients receiving RT. Median follow-up was 83 months.
Results: The actuarial 5-year rates of locoregional relapse were 1% to 3% for PORTEC patients who received RT, compared with 14% for stage IC, grade 3 patients. Five-year distant metastases rates were 3% to 8% for grade 1 and 2 tumors; 20% for stage IB, grade 3 tumors; and 31% for stage IC, grade 3 tumors. Overall survival rates were 83% to 85% for grades 1 and 2; 74% for stage IB, grade 3; and 58% for stage IC, grade 3 patients (P <.001). In multivariate analysis grade 3 was the most important adverse prognostic factor for relapse and death as a result of endometrial cancer (hazard ratios, 5.4 and 5.5; P <.0001).
Conclusion: Patients with stage IC, grade 3 endometrial carcinoma are at high risk of early distant spread and endometrial carcinoma-related death. Novel strategies for adjuvant therapy should be explored to improve survival for this patient group.