Impact of endometrial carcinoma histotype on the prognostic value of the TCGA molecular subgroups

Background: The Cancer Genome Atlas (TCGA) identified four prognostic subgroups of endometrial carcinoma: copy-number-low/p53-wild-type (p53wt), POLE-mutated/ultramutated (POLEmt), microsatellite-instability/hypermutated (MSI), and copy-number-high/p53-mutated (p53mt). However, it is still unclear if they may be integrated with the current histopathological prognostic factors, such as histotype. Objective: To assess the impact of histotype on the prognostic value of the TCGA molecular subgroups of endometrial carcinoma. Methods: A systematic review and meta-analysis was performed by searching 7 electronic databases from their inception to April 2019 for studies assessing prognosis in all TCGA subgroups of endometrial carcinoma. Pooled hazard ratio (HR) for overall survival (OS) was calculated in two different groups (“all-histotypes” and “endometrioid”), using p53wt subgroup as reference standard; HR for non-endometrioid histotypes was calculated indirectly. Disease-specific survival and progression-free survival were assessed as additional analyses. Results: Six studies with 2818 patients were included. In the p53mt subgroup, pooled HRs for OS were 4.322 (all-histotypes), 2.505 (endometrioid), and 4.937 (non-endometrioid). In the MSI subgroup, pooled HRs were 1.965 (all-histotypes), 1.287 (endometrioid), and 6.361 (non-endometrioid). In the POLEmt subgroup, pooled HRs were 0.763 (all-histotypes), 0.481 (endometrioid), and 2.634 (non-endometrioid). Results of additional analyses were consistent for all subgroups except for non-endometrioid POLEmt carcinomas. Conclusion: Histotype of endometrial carcinoma shows a crucial prognostic value independently of the TCGA molecular subgroup, with non-endometrioid carcinomas having a worse prognosis in each TCGA subgroup. Histotype should be integrated with molecular characterization for the risk stratification of patients in the future.