Carcinoembryonic antigen is one of the tumor markers, but it is not specific. The high limit of normal value of carcinoembryonic antigen is 5ng/mL, but the high limit of normal value may be slightly different due to different testing kits of each unit. Carcinoembryonic antigen 13.5ng/mL is greater than the high limit of normal value, but not more than 3 times, so it cannot be said that there is a tumor in the body and needs to be investigated. Carcinoembryonic antigen 13.5ng/mL can also be seen in inflammation in the body such as pneumonia, gastritis and enteritis. If no tumor is found in the body after examination, the carcinoembryonic antigen can be rechecked after one month, and if it decreases, the recheck can be stopped, and if it continues to increase, it can be rechecked after one month.