The Kaplan–Meier plotter database further demonstrated that CD274 (PD-L1) mRNA expression was not associated with OS in 655 patients with ovarian cancer (all datasets analysis) and in seven datasets which were analyzed separately, including GSE18520 (n = 53), GSE19829 (n = 28), GSE26193 (n = 107), GSE27651 (n = 39), GSE30161 (n = 50), GSE63885 (n = 25) and GSE9891 (n = 285) (each p > 0.05, Additional file 4: Fig. S4a–h). This evidence concerns the gene CD274 and ovarian cancer.