The blood-borne CTCs of metastatic patients differed in expression of 55 mRNAs and 9 miRNAs from the CTCs of PTs and blood samples which is indicative of a molecular selection pressure exerted by minimally expressed miRNAs that are responsible for the emergence of receptor negative metastatic tumor cell fractions from estrogen receptor positive (ER+) PT cohort [51]. This evidence concerns the gene EREG and neoplasm.