The forest plot indicated that KCC2 expression markedly predicted prognosis in GBM (OS, p = 0.0237; PFS, p = 0.0209), KIRC (OS, p = 0.0006; PFS, p < 0.0001), PRAD (OS, p = 0.0003; PFS, p = 0.0015), and THCA (OS, p = 0.0009; PFS, p < 0.0001). This evidence concerns the gene SLC12A5 and glioblastoma.