CA50 is a kind of glycoantigen, even if it is very high, more than 100U/L or 200U/L, it cannot confirm the diagnosis of cancer. CA50, also known as glycoantigen 50, may be elevated in malignant tumors of the gastrointestinal tract. However, sometimes it may be slightly elevated, but it may only be an inflammatory lesion, not necessarily cancer. There may be other benign tumors, such as peptic ulcers, that may also have elevated CA50. The diagnosis of cancer cannot be confirmed by tumor markers alone, but also by imaging, gastroscopy, colonoscopy and other endoscopic examinations, which are the basis of preliminary diagnosis, and pathological examination is needed to confirm the diagnosis.