ERBB2 and breast cancer: In 2012, a study involving about 500 patients with non-metastatic breast cancer revealed that, although CTC positivity was 19% as assessed by detecting at least one epithelial and breast cancer-associated transcript among EPCAM, MUC1 and ERBB2, 90% of samples expressed at least one EMT-related gene among PIK3CA, AKT2 and TWIST1 based on cut-off values set in a case series of 30 healthy donors, an 18% of cases negative for epithelial or breast cancer markers were positive for at least one of the EMT genes [158].