CEACAM5 and breast cancer: For current disease progression monitoring for breast cancer patients, simultaneous use of the two serum markers CA-153 and carcinoembryonic antigen (CEA) shows that the early diagnosis of metastasis in up to 60–80% of patients with breast cancer is not sensitive enough to monitor disease progression in real time (Dawson et al. 2013; Duffy et al. 2010; Banin Hirata et al. 2014).