Tumor indicators, also known as tumor glycoantigens, are some clinical indicators related to tumors, mainly the glycoantigen molecules of tumor cells. Tumor indicators are mainly used for the diagnosis of malignant tumors, monitoring of tumor progression and determining the efficacy of treatment. Commonly used ones are: AFP, CEA, CA19-9, CA72-4, CA153, CA50, CA242, CA125 and so on. These indicators are very helpful for early detection of tumor and determination of tumor progression and treatment effect. However, because the indicators themselves only have certain correlation with the tumor condition, and there are more influencing factors affecting these indicators, the accuracy and precision of tumor indicators are somewhat lacking. A few patients with high tumor indicators rise, but the final diagnosis is not malignant tumor. As for the accuracy of a certain index indicating the origin of tumor is relative, not absolutely reliable. For example, elevated CA199 only indicates that pancreatic and digestive tract tumors are more likely, but tumors in other areas are also possible. In addition, the degree of elevation of the index and the severity of the tumor disease are not proportional to each other. For this reason, several tumor indicators are often tested at the same time in order to improve their accuracy and precision in clinical practice. So how to judge the significance of elevated tumor indicators? What should be done when tumor indicators are high? Generally speaking, a slight increase of single index (<50%) can be reviewed regularly and observed closely; if multiple indexes increase several times, a comprehensive examination such as CT and B-ultrasound should be conducted. It is advisable to seek consultation from oncologists (not other specialists) to determine the significance of elevated tumor indicators and their countermeasures.