Tumor markers are a class of substances that respond to the presence of tumors and are found in much higher amounts in tumor patients than in healthy people. The presence or quantitative change of tumor markers can indicate the nature of tumor, which has now become an important auxiliary tool in tumor diagnosis, prognosis and treatment guidance. Currently, the commonly used hematological tumor tests include: lung cancer tumor marker group (CEA, Cyfra21-1, NSE, etc.), digestive tract tumor marker group (CEA, CA199, CA242, etc.), CA153 (breast cancer, etc.), CA125 (ovarian cancer, etc.), AFP (liver cancer, etc.), PSA (prostate cancer, etc.), HCG (choriocarcinoma, etc.), which require 5-10ml of blood is drawn for laboratory tests, and its screening significance lies in its early suggestive role. The level of tumor markers will increase when many cancers occur, such as ovarian cancer, prostate cancer, liver cancer, etc. They are more specific cancers and tumor markers will reflect the presence of cancer; however, for some less specific cancers, such as lung cancer, stomach cancer, intestinal tumors, etc., patients often do not have abnormal tumor markers. For example, alpha-fetoprotein (AFP) is a very common tumor marker that can detect more than 80% of liver cancers and most genital tumors, such as ovarian cancer. However, AFP can also be elevated with benign diseases, including hepatitis, cirrhosis, enterocolitis, and hereditary tyrosinemia, and can also be temporarily elevated in pregnancy. Nowadays, many people ask for tumor marker tests during outpatient physical examinations, but they are often afraid when some values increase. If there is a very significant increase in tumor marker test value, cancer suspicion is very high and further examination should be done. If the elevation persists, one should suspect that a tumor is developing; if there has been no significant elevation, it is usually a benign lesion, probably inflammatory. However, if tumor markers are found to be persistently elevated after surgery in cancer patients, the possibility of recurrence should be considered. In clinical practice, various tumor markers can only be used as one of the auxiliary diagnostic indicators, and we must combine them with other imaging examinations to give a clear answer. Wenlan Cao, Department of Oncology, Xiyuan Hospital, Chinese Academy of Traditional Chinese Medicine Recently, researchers found that before the formation of malignant tumor, a small amount of abnormal cells already exist in the patient’s blood, and for some diseases such as leukemia, the change of blood cells is even a direct indicator. For example, patients suffering from blood cancer will have a high percentage of white blood cells in their blood, and cancer cells are generally larger than normal cells, making them quite easy to identify. Researchers have invented new biochips that require only a single drop of blood for blood cell counting and separation, which can reveal information about cancer and other diseases. The advantage of the test method is that the patient does not need to undergo surgery, and only a small blood sample can be taken to measure whether the patient has cancer. In this way, the patient can detect the disease early and receive treatment, and has a better chance of being cured. Although this test chip has high sensitivity, the biochip is only suitable for pre-detection of certain diseases because blood and cells are very complex systems. If cancer or other diseases are detected, they still need to be combined with traditional testing methods and cross-referenced to confirm the diagnosis. Researchers from the M.D. Anderson Cancer Center in Texas claim that we should be able to sequence the genetic material in blood samples to identify any genetic mutations that represent the presence of cancer. They believe that this would open up a whole new field of research and that such exosomal samples would contain DNA that is present in all cells in the body, and that such particles could be investigated to see if they might carry additional information about any cancer cells in the body. If we can make a significant breakthrough in this area, then in the near future, a single drop of blood taken could help us detect abnormal signals early, diagnose them early and get timely treatment.