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Cancer biomarker: the classification, principle and characteristics

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  1. What is a biomarker?

Biomarkers are biochemical indicators that can be used to label changes in systems, organs, tissues, cells, and subcellular structures or functions, or to make changes, by measuring biochemical, cellular, and tissue responses, using biochemistry, immunology. genetics and other methods to indicate the presence or absence of pollutants and the response of biological individuals. Biomarkers can be directly sensitive to target cells or target molecules in vivo. Biomarkers have a very wide range of uses and can be used for disease diagnosis, for judging disease staging, or for evaluating the safety and efficacy of new drugs or new therapies in the target population.

Biomarkers are a necessary complement to conventional bioassays and can be used to form a complete biomonitoring system. In addition to chemical testing, a complete and comprehensive monitoring system needs to consider biological effects at various tissue levels, including individual or sub-individual levels, as well as biological effects at the population and community levels. Using advanced proteomics techniques to find relevant biomarkers in samples, surface-enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF-MS) can be used to screen disease-associated biomarkers using reversed-phase high performance liquid chromatography (RP-HPLC was used to separate and purify the sample, and the target protein was tracked by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The potential protein markers were identified by LC-MS/MS.

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  1. Classification of biomarkers

Based on functions, biomarkers are generally divided into:

Nutritional biomarkers (marker of exposure): reflect the content of exogenous substances or their metabolites or exogenous substances interacting with certain target cells and target molecules in the biological material of the organism, including two types of markers reflecting internal dose and biological effect dose.

Effect Biomarkers: Indicators of biochemical, physiological, behavioral, or other changes that can be measured in the body, including early biological effects, structural or functional changes, and markers of disease.

Sensitive biomarkers: reflects the body's innate or acquired indicators of its ability to respond to exposure to exogenous substances.

  1. Principles of biomarker selection

(1) The selected biomarker must have a certain specificity.

(2) The selected biomarker must have sufficient sensitivity that the level of the selected marker has a dose-response relationship with the level of external contact, and this relationship can be maintained at the level of innocuous contact.

(3) Repeatability and individual differences in the selected biomarker analysis are within acceptable limits.

(4) The selected biological standard should have sufficient stability to facilitate the transportation, preservation and analysis of the sample.

(5) When sampling, it is best to be non-destructive to the human body and acceptable to the subject.

  1. Characteristics of biomarkers:

(1) Has a certain sensitivity, the sensitivity should be higher than the general biological detection index, can be measured at low dose, and can be operated in a small amount. (2) Has the time effect of the reaction. The reaction must have a certain settling time and be fast. (3) The effect of the effector markers on the molecular and biochemical levels is closely related to the effects at the advanced biological level (such as growth and reproduction), and the effects at all levels must have a causal relationship. (4) Has a certain field application value. (5) It is required to select indicators that have less damage to the tested organisms, and the technology is easy to grasp. (6) Specific and early warning (eg, AchE).

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  1. How do you detect biomarkers in different cancers?

World Health Organization (WHO) statistics show that more than 80% of early malignancies can be cured! Early detection, early diagnosis, and early treatment are the keys to success. Therefore, how to detect cancer early to reduce mortality has become the focus of cancer prevention. In addition to clinical signs and imaging methods (such as X-ray, CT, MRI, B-ultrasound, colonoscopy, gastroscopy, etc.), early detection of cancer by tumor markers has become more and more important.

Tumor markers are biological signals that reflect the biological behavior of tumors. Combined detection of multiple tumor markers can detect tumors earlier than routine examinations (such as physical examination, X-ray, CT, MRI, B-ultrasound), and gain valuable time for treatment. Tumor marker detection can be used to: screening healthy populations, high-risk populations with family history or high risk factors; as a basis for early diagnosis, differential diagnosis, treatment testing, efficacy evaluation, recurrence and metastasis, prognosis, and search for therapeutic targets; tumors are detected early in asymptomatic conditions. For symptomatic people or high-risk populations, tumor markers have great reference value as indicators for census and health examinations. For example, elevated alpha-fetoprotein may indicate an increased risk of liver cancer in people who have had hepatitis and liver damage. Detection of prostate specific antigen (PSA) in elderly population tests is also a primary reference for male prostate cancer. For subjects with positive initial detection of tumor markers and no abnormalities, it is recommended to check every four to six weeks. If the retest result is negative, the possibility of tumor exclusion is naturally excluded (probably a transient increase in benign disease); if it continues to be positive for three consecutive times, it should be highly valued, consult a specialist, ask for a detailed history and conduct a physical examination. And combined with a variety of imaging examinations for tumor

There are many kinds of biomarkers, such as disease markers, cancer biomarkers, immune biomarkers, etc. So, how do we detect different biomarkers?

An example of a tumor marker is examined: liver cancer. Hepatitis B virus carriers, men who love to drink alcohol, check alpha-fetoprotein and B-ultrasound every six months after age 35. Liver cancer is a relatively high-risk disease in China. The high-risk age is 40-50 years old. Its important cause is viral infection--hepatitis, especially hepatitis B and hepatitis C, and even hepatitis carriers. These people are very likely to develop liver cancer after the age of 40.


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