CEACAM5 and cancer: As mentioned above, early diagnosis of BC is crucial for survival prognosis, but despite the fact that we already have some cancer biomarkers such as tissue receptor expression (Estrogen Receptor (ER), Progesterone Receptor (PR), HER2) that are vital for staging or blood biomarkers, like Cancer Antigen (CA) 15-3, CA27-29, and Carcinoembryonic Antigen (CEA), these have limited sensitivity in early BC [34].