Common reasons for CEA elevation: 1) CEA will be significantly increased when there are malignant tumors such as pancreatic cancer, colon cancer, breast cancer, etc. 2) CEA will be mildly increased when there are benign diseases in the body, such as colitis, pancreatitis, emphysema and bronchial asthma. Therefore, if CEA is significantly elevated, it is highly suspected that there is a malignant tumor in the body. If it is mildly elevated, it may be a benign disease, but it does not exclude the absence of malignant tumors in the body. Even if there are malignant tumors as mentioned above, some patients will have CEA values within the normal range from the beginning to the end.