CEACAM5 and cancer: Specific quantification of cancer biomarkers can be helpful in the early cancer detection, categorization, severity level, and assessment of resistance to chemotherapy.[6, 7, 8, 9, 10, 11] Precise recognition of prostate‐specific antigen (PSA) helps to examine prostate cancer,[12, 13, 14, 15] carcinoembryonic antigen (CEA) for colon cancer,[16, 17, 18, 19, 20]α‐fetoprotein (AFP) for liver cancer,[11, 21, 22, 23, 24] neuron‐specific enolase (NSE) for lung cancer,[25, 26, 27, 28, 29] and ferritin for breast and pancreatic cancers.[30, 31, 32, 33, 34, 35]