Nowadays, EpCAM-based CTC detection technologies are widely applied for BC [68]; however, they have some limitations: (i) not all BC express EpCAM, therefore it cannot be used in EpCAM-negative or low-expressing tumors [69]; (ii) moreover, different markers, including EpCAM, are down-regulated during EMT, which affects the detection rate of EpCAM-positive CTCs [70]. The gene discussed is EPCAM; the disease is breast cancer.