Tumor markers are secreted by tumor cells or produced by the body in response to tumors during the formation and development of tumors, and have a prompting effect on the existence and changes of tumors. Clinically, tumor markers play an important role in the screening of high-risk groups of tumors, early diagnosis of tumors, curative effect monitoring, prognosis evaluation, and recurrence monitoring. Accurate determination of tumor marker test is very important to assist in guiding clinical diagnosis and treatment, so it is necessary to exclude the influence of various factors.
For the determination of tumor markers, there are currently no international standards except for AFP and CEA, which brings difficulties to the quality control and standardization of tumor marker determination. In terms of methodology, there are many tumor marker test methods, such as radiometric assay, enzyme-linked immunoassay, chemiluminescence immunoassay, etc. Each assay method has its own precision and repeatability. Manual operation has poor repeatability and large error; automated measurement has good repeatability and small error.
Different kits also have differences in assays, which may be caused by different sites of mAbs against antigens. Even with the same antibody, different results may be obtained due to antigenic heterogeneity or matrix effects. The main cause of inter-assay error is the lack of standardization of assays, including the lack of uniform antigens, antigen components, calibrators, and reference methods. In particular, during the continuous monitoring of patients, the examination should be performed in the same laboratory as much as possible, and changes to the analytical system (including instruments and reagents) should be avoided. In addition, laboratories should strictly implement internal quality control standards.
Since neuron-specific enolase (NSE) is also present in erythrocytes and platelets, hemolysis of the specimen can increase the concentration of NSE in the blood. Usually, blood samples should be centrifuged in time after collection, stored in a refrigerator at 4°C, and measured within 24 hours; serum that cannot be measured within 24 hours should be stored in a refrigerator at -20°C; specimens that need to be stored for a long time should be stored at -70°C, and repeated freezing and thawing should be prevented. Enzymes and hormones TM are unstable and easy to degrade, so they should be measured in time or separated from serum for cryopreservation. In addition, in vitro coagulants interfere with some TMs; contamination of specimens such as respiratory secretions, saliva, and sweat can increase SCC, CA199, and CEA.
The study found that the overall reference value of Chinese healthy population was slightly different from that of apparently healthy Western women. Among them, age is an important factor affecting the expression of HE4 levels, and HE4 levels in healthy people increase with age; at the same time, menopausal status is another important factor affecting HE4 levels in apparently healthy people, and HE4 levels increase significantly after menopause. Abnormal liver function, poor biliary excretion, bile stasis, etc. can cause increased concentrations of CEA, alkaline phosphatase, glutamyl transferase and cytokines. Cytokeratin 19 fragment, squamous cell carcinoma antigen, and β2-microglobulin can be elevated in renal insufficiency. Age has a significant effect on the concentration of tumor markers detected, with one study showing that at least 40% of healthy individuals aged 66-99 had an increase in one. In some women, CA125 and CA199 can be elevated during menstruation. Alpha-fetoprotein and CA125 were significantly increased during pregnancy. Elevated CEA is seen in some long-term smokers.
