Introduction/Background We recently identified low vimentin as a marker of recurrence in low-stage endometrial cancers (Lien et al. eBioMedicine, Volume 92, 2023). Such markers are currently lacking in clinical use and could improve treatment for patients with undetected high-risk of recurrence. We aimed to validate the robustness of vimentin as a marker for poor prognosis in endometrial cancer.

Methodology Imaging mass cytometry was used to examine single-cell expression of 23 proteins in 36 primary FIGO IB endometrial cancers, of which 17 recurred. Single-cell information was extracted for each tumor and unsupervised clustering was used to identify cellular phenotypes. Vimentin protein expression was evaluated by immunohistochemistry (IHC) in preoperative samples. Results were validated in preoperative and operative samples. Protein expression in paired primary and metastases was investigated.

Results The abundance of epithelial, immune or stromal cell types did not associate with recurrence, however a distinct epithelial phenotype characterized by low vimentin was more prevalent in recurrent tumors. Loss and low expression of vimentin was validated by IHC as a robust marker for recurrence in FIGO I stage disease and predicted poor prognosis in endometrioid patients only and in the full cohort.

Conclusion This study reveals distinct characteristics in low-stage tumors and identifies and validates vimentin as a clinically robust marker for poor prognosis in endometrial cancer.

Disclosures The authors declare no competing interests.