CEACAM5 and cancer: In this review, electrochemical sensing systems will be discussed and their applications in quantification of a number of cancer biomarkers, including oncogene-related nucleic acids (DNA or RNA), proteins (carbohydrate antigen, carcinoembryonic antigen, enzymatic tumor markers, etc.), and small molecules (reactive oxygen species (ROS) and reactive nitrogen species (RNS)), will be considered.