Colorectal carcinoma is the cancer developed in the colon or rectum of the digestive system. In developed countries, it is the most common cancer in aging population. Genetic deposition and a less active life style contribute to the development of the cancer. Molecular pathological study showed that altered Wnt-APC-?-catenim signalling pathway, mutated p53, and deactivated TGF-? and DCC (Deleted in Colon Cancer) are involved with the pathogenesis. The cancer is currently screened with a fecal occult blood test in people over 50 years old and the malignancy is confirmed by tumour biopsy. The search for specific biomarker for non-invasive test is still ongoing. Tumour associated antigen, TAG-72, is a high molecular weight glycoprotein found at the cell surface in a variety of cancers including gastric cancer, ovarian cancer, colon cancer, breast cancer and pancreatic cancer. It has been used as a tumour marker and therapeutic target for cancer treatment.