Prognostic implications of tumour‐infiltrating lymphocytes for recurrence in epithelial ovarian cancer

The recurrence of patients with epithelial ovarian cancer (EOC) is largely attributed to tumour cells escaping from the surveillance of immune cells. However, to date there is a lack of studies that have systematically evaluated the associations between the infiltration fraction of immune cells and the recurrence risk of EOC. Based on the micro‐ribonucleic acid (microRNA) expression profiles of 441 EOC patients, we constructed a microRNA‐based panel with recurrence prediction potential using non‐negative matrix factorization consensus clustering. Then, we evaluated the association between recurrence risk and infiltration proportions among 10 immune cell types by CIBERSORT and a multivariable Cox regression model. As a result, we identified a 72‐microRNA‐based panel that could stratify patients into high and low risk of recurrence. The infiltration of plasma cells and M1 macrophages was consistently significantly associated with the risk of recurrence in patients with EOC. Plasma cells were significantly associated with a decreased risk of relapse [hazard ratio (HR) = 0.58, p  = 0.006), while M1 macrophages were associated with an increased risk of relapse (HR = 1.59, p  = 0.003). Therefore, the 72‐microRNA‐based panel, M1 macrophages and plasma cells may hold potential to serve as recurrence predictors of EOC patients in clinical practice.