CEA is a tumor marker that is mainly found in malignant tumors of the digestive system, such as gastric cancer, rectal cancer, pancreatic cancer, liver cancer, and malignant tumors will all show some degree of CEA elevation, like pregnancy and ovarian cancer may also show CEA elevation. Pneumonia is mainly caused by bacterial infection and does not result in elevated CEA. Clinically, pneumonia mainly manifests as cough, coughing, high fever or chest pain, occasionally blood in the sputum, and obvious wet rales can be heard in the lungs. Once a patient with pneumonia is diagnosed, he or she should be treated with active anti-infection therapy and symptomatic support therapy, drinking warm water, taking rest, and maintaining adequate calories and protein.