Carcinoembryonic Antigen (CEA) is a non-specific tumor marker often found in the blood. High levels of CEA are commonly associated with the progression of wide range of tumors. It is currently used as a biomarker for malignant tumors of the lung and colon, but due to its limited specificity and clinical implication, it can be used only for monitoring rather than tumor diagnosis.1 Certain non-malignant conditions like diabetes mellitus and gastric disease may also affect the CEA levels. These may be relevant particularly in early stages of colorectal cancers. Hence, elucidating the factors that affect the CEA levels might improve the accuracy and utility of its measurement.