DKK1 and pancreatic adenocarcinoma: Various studies also demonstrated the effect of DKK1 on the prognosis of certain cancers, such as head and neck squamous carcinoma (HNSC), NSCLC, and pancreatic adenocarcinoma (PAAD) (Yamabuki et al., 2007; Han et al., 2015; Gao et al., 2018).