In fact, except for AFP, which is helpful for the early diagnosis of primary liver cancer, and PSA, F-PSA and their ratios, which are helpful for the early diagnosis of prostate cancer, other tumor markers are not of great significance for the early diagnosis of tumors, and their clinical value is mainly reflected in the analysis of efficacy, prognosis, and prediction of recurrence and metastasis. The early diagnosis of tumor needs to be combined with medical history, symptoms, physical signs, imaging examination (ultrasound, CT, X-ray, gastroscopy, colonoscopy) and other means for comprehensive analysis, while the definite diagnosis needs to rely on pathological examination. Can negative tumor markers exclude related tumors? Since most tumor marker tests are not of great significance for early diagnosis of tumors, a negative tumor marker cannot completely exclude related tumors. Even for tumor markers like AFP, which is quite significant for the early diagnosis of primary liver cancer, its positive rate only reaches 79%-90% (the positive threshold for AFP to diagnose primary liver cancer is >400ng/ml). In other words, there are still 10%-30% of patients with primary liver cancer who have normal or only mildly elevated AFP. Can an abnormal tumor marker diagnose an associated tumor? Many benign diseases can have abnormal tumor markers, for example, prostatic hypertrophy and prostatitis can have mild to moderate elevation of PSA, endometriosis can have mild to moderate elevation of CA125, and acute and chronic liver disease can have different degrees of elevation of CA125, CA199, CA50, and ferritin. Biliary tract disease with jaundice often has significant elevations of CA199 and CA50, and even long-term smokers may have mild elevations of CEA. What is the value of mild elevation of tumor markers? Because many benign diseases can have abnormal tumor markers, some people think that a mild elevation of tumor markers is of little value, and that it is only meaningful if it is more than 5 times the normal reference value. This is not true because in most cases, the range of normal reference values is set relatively wide. Therefore, even a mild elevation of a tumor marker can be of great value after benign disease has been excluded. How to make better use of tumor markers? Tumor marker testing should be performed as soon as possible for those with family history of tumor or clinical suspicion of symptoms. For example, the preferred tumor markers for lung cancer are CEA, NSE and CY211, and the supplemental tumor markers are SCCA, TPA, ACTH and calcitonin; the preferred tumor marker for liver cancer is AFP, and the supplemental tumor marker is CEA, as well as alkaline phosphatase (ALP), r-glutamyl transferase (GTP), etc. Glutamyl transferase (GGT), etc. For those who have positive initial tumor marker test results without any abnormalities, regular rechecking is recommended. If the recheck result is negative, it may be a transient elevation caused by benign disease. If the test is negative, it may be a transient elevation due to benign disease. If the test is consistently positive for three consecutive times, it should be taken seriously with detailed medical history, physical examination and imaging. If the tumor marker is persistently positive and no positive sign is detected for a while, it is recommended to continue to follow up regularly. The application of tumor markers lies in dynamic observation, rational application and joint testing, which is more beneficial to the prevention and treatment of tumor.