Two recent ionomic studies investigated the complex relationship among trace elements in toenails, KRAS mutations, and survival in pancreatic ductal adenocarcinoma (PDAC, the most common form of PaC), which not only suggested a special role for several trace elements (such as Ni and Mn) in pancreatic and perhaps other cancers with KRAS mutations, but also found a strong association between higher toenail concentrations of heavy metals (such as Pb, Cd, As, and V) and better survival of PDAC [150,151]. This evidence concerns the gene KRAS and cancer.