Over the last 15 years it has become increasingly clear that dysregulated expression, splicing, and/or function of ion channels and transporters (ICT) occur in all cancers. Being linked to the widely accepted hallmarks of cancer, ICTs represent novel therapeutic, diagnostic, and prognostic targets. To discuss the current status of the field, a colloquium on "Ion Transport and Cancer" was held, covering the roles of ICTs in cancer cell proliferation, apoptosis, motility, and invasion, and in both the generation of and the interaction of the cancer cells with the tumor environment. Additional sessions dealt with pancreatic ductal adenocarcinoma and transport protein-based therapeutic and diagnostic concepts. There was overall consensus that essential contributions of ICT dysregulation to the cancer process have been demonstrated. Future research should be directed toward further elucidating the mechanisms and developing therapeutic applications.