Both CA199 and CA242 are tumor markers suggestive of tumors of epithelial origin. The main purpose of conducting these two tests in clinical practice is to monitor and determine the presence of tumors of gastrointestinal origin, such as pancreatic cancer, colon cancer, and rectal cancer. If both CA199 and CA242 are found to be elevated clinically, it is necessary to do a CT scan and enhancement of the whole abdomen, as well as colonoscopy and proctoscopy, to rule out the presence of tumors of this area. If these two indicators are elevated a lot at the same time, the above mentioned tests must be done to clarify the presence of tumor. If it is not clear, some CT examinations can be done to see if there are any lesions with elevated metabolism in hidden areas. Puncture biopsy can be done for lesions with elevated metabolism to clarify the presence of tumor.