CA199 and CA242 are tumor markers that can be elevated in certain tumors, but they do not have clear specificity, and not all increases in CA199 and CA242 are tumors. Generally speaking, tumor markers cannot be used as a basis for diagnosing malignant tumors, especially when they are slightly higher than the normal value, which is often not of great clinical significance. If there is no corresponding clinical manifestation or examination result, only blood sampling for tumor markers is often used as routine screening or regular follow-up. If the value of both is significantly higher than normal or several times or tens of times higher than normal, this is when it has a stronger clinical significance.