DKK1 and cancer: The differential expression of DKK1 has been reported in many different cancers; however, there is a lack of comprehensive pan-cancer analysis of DKK1. In the current study, after analyzing the expression level of DKK1 in cancer and normal tissues of 33 cancer types, we found that DKK1 was upregulated in CHOL, ESCA, HNSC, LIHC, LUSC, and STAD, but downregulated in BLCA, KICH, KIRP, and PRAD.