ABSTRACT
BACKGROUND: Survival benefits of post-operative systemic and radiation therapy in high-risk stage I endometrial cancer are uncertain. OBJECTIVE: To compare recurrence patterns and survival outcomes of post-surgical treatment in patients with high-risk stage I endometrial cancer and to determine whether adjuvant therapy significantly improves outcomes. METHODS: High-risk stage I endometrial cancer was defined as either stage IB grade 3 endometrioid histology or myoinvasive non-endometrioid histology. Consecutive patients diagnosed between January 2000 and December 2010 in eight cancer centers were included. Patients, disease, and treatment characteristics were summarized by descriptive statistics. Overall survival, disease-specific survival, and relapse-free survival were examined using Cox's proportional hazards regression and log-rank test. Survival curves were estimated using the Kaplan-Meier method. RESULTS: Of 2317 patients with stage I endometrial cancer, 414 patients had high-risk disease. Use of chemotherapy did not improve overall survival (relative risk (RR) 0.70, 95% CI 0.46 to 1.14, p=0.13) or disease-specific survival (RR 1.06, 95% CI 0.61 to 1.85, p=0.84). Significant improvement in recurrence-free survival was observed in patients who received chemotherapy (RR 0.61, 95% CI 0.39 to 0.95, p=0.03). Use of radiation therapy did not improve overall survival, recurrence-free survival, or disease-specific survival. Patients who received four cycles or fewer of chemotherapy versus five to six cycles had similar overall survival, disease-specific survival, and recurrence-free survival. CONCLUSIONS: Post-operative chemotherapy or radiation in stage I high-risk endometrial cancer is not associated with improved cancer-specific or overall survival. More than four cycles of chemotherapy did not improve survival compared with four cycles or fewer.
