The normal value of carcinoembryonic antigen ranges from 0 to 5ng/mL. Although 15ng/mL is a bit high, it is not necessarily cancer, it may be caused by inflammation such as chronic gastritis, chronic cholecystitis, etc., which should be analyzed specifically. Carcinoembryonic antigen (CEA), as a common tumor marker, is elevated in lung adenocarcinoma, colorectal cancer, etc. However, tumor marker cannot be used to diagnose cancer, but can be used to monitor the efficacy of anticancer treatment, prognosis, metastasis, etc. To confirm the diagnosis, the systemic lesion should be clarified and pathological biopsy should be taken from the diseased tissues and a positive biopsy can be confirmed to diagnose cancer. If CEA is elevated to 15ng/mL, chronic inflammation, such as chronic gastritis, chronic cholecystitis, etc., may lead to the elevation of carcinoembryonic antigen. It is recommended to review the carcinoembryonic antigen in time. If it is persistently elevated, even more than ten or tens of times higher than the normal value, one should be alerted to the risk of cancer.