Canadian high risk endometrial cancer (CHREC) consortium: Analyzing the clinical behavior of high risk endometrial cancers

• We outline the rate of recurrence and overall survival in high risk endometrial cancers.
• Lymphovascular invasion and omental involvement varies by histotype.
• Location of recurrence and stage distribution vary by histotype.

ObjectivesThe objective of this study is to analyze the clinical behavior of endometrial carcinomas by high risk(HR) histotype, including stage, overall survival, recurrence free survival and patterns of failure.MethodsThis is a retrospective multi-institutional cohort study performed at 7 tertiary care centers across Canada between 2000 and 2012 and included: grade 3 endometrioid (EC3), endometrial serous cancer (ESC), clear cell carcinomas (CCC) and carcinosarcoma (CS). Clinicopathological and outcome data was collected.Results1260 women with endometrial carcinoma with 1013 having staging procedures were identified; 398 EC3, 449 ESC, 236 CS and 91 CCC. 51.8% had lymphovascular space invasion (LVSI) and 18.5% had omental involvement with a statistically significant difference between tumor types (p = 0.0005 and 0.0047 respectively); ESC had a significantly greater rate of omental involvement compared to EC3 (22% to 9%, p = 0.0005). Within the entire cohort 49.3% were stage 1, 10.6% were stage 2, 27.4% were stage 3 and 12.7% were stage 4. Overall survival and recurrence free survival were significantly different between histotypes (p < 0.0001) with CS having the worst outcome. Overall 31.5% of patients recurred. CS and ESC had a higher distant recurrence rate compared to EC3 (29.6%, 31.0% compared to 16.4%, p = 0.0002 and p < 0.001).ConclusionThis study is one of the largest clinical cohorts of HR endometrial cancers. We have further clarified the impact of histotype and stage on recurrence and survival, and the high likelihood of distant recurrence. However, the differences are modest and risk prediction models will require additional molecular markers.