CLDN6 and cancer: In order to provide a more systematic and comprehensive insight of CLDN6, to the best of our knowledge, we are the first to explore the expression and biofunction of CLDN6 from the perspective of pan-cancer, focusing on its diagnostic and prognostic values, and find that CLDN6 is not only significantly upregulated in 20 types of human cancers but also differently expressed in different molecular subtypes of seven cancer types and different immune subtypes of nine cancer types.