CEACAM5 and colorectal carcinoma: CEA is the most well‐characterized CRC blood‐based biomarker.4 Using two unique peptides, and the log transformed AUC for matched y‐ and b‐ion transitions (minimum of four with MS2 accuracy <10 ppm), we used Mann–Whitney U Wallis nonparametric testing to determine statistical differences between CEA pre‐ versus post‐operation.