KRT19 and breast carcinoma: In a recent study that included 312 patients with early breast cancer monitored for cytokeratin (CK)-19 mRNA positivity in peripheral blood during follow-up, we reported that 53.8% of patients had detectable CK-19 mRNA CTCs on at least one time point between the third and fifth year of follow-up and that persistence of CK-19 mRNA-positive CTCs during the first 5 years was associated with increased risk for late relapse and death [29].