CK-19 is expressed in the majority of breast carcinomas (Bartek et al, 1985) and has been extensively used as a marker for CTC (Slade et al, 1999; Smith et al, 2000; Aerts et al, 2001; Stathopoulou et al, 2003; Benoy et al, 2004; Ring et al, 2005). This evidence concerns the gene KRT19 and breast carcinoma.