RRM2 and cancer: High RRM2 expression was observed in 19 cancers via TCGA: BLCA, BRCA, CESC, CHOL, COAD, ESCA, GBM, HNSC, KIRC, KIRP, LIHC, LUAD, LUSC, PCPG, PRAD, READ, STAD, THCA and UCEC (Figure 1A).