Tumor marker test and cancer diagnosis

2021-07-05 04:13 PM

One can use many different methods such as physical methods, pathological methods, and biochemical methods through identifying cancer markers.

Cancer (K) is one of the diseases with the highest mortality rate. There are many cancers depending on where it arises such as K lung, K breast, K colon, K nasopharynx, K bladder, K liver… Cancer in different places has different mortality rates.

Factors that cause cancer

Chemical substances such as polycyclic hydro carbide (HCPC).

Physical factors such as X-rays, α, β...

Biological factors such as hepatitis B virus (HBV), hepatitis C virus (HCV). HBV and HCV are two viruses capable of causing primary liver cancer.

Diagnosis of cancer (K)

People can use many different methods such as physical methods, pathological methods and biochemical methods through the determination of tumor markers "Tumor marker". Each method has its own advantages and disadvantages. For example, pathology provides us with "golden" information about the tumor but psychologically limits the pain of aspiration biopsy. The "immuno-enzyme" biochemical method accurately identifies Tumor markers, just need to take blood or urine for easier testing, also gives the exact nature of cancer without causing much pain to the patient.

Tumor marker - a marker of cancer - a marker of cancer, including substances with

Is a substance produced by K cells, which is introduced into the blood as AFP, CEA, CA-125, CYFRA 21-1...

Is a hormone-like β-HCG or a metabolite like CPR (Active Protein C), LDH, GGT.

Mechanism of carcinogenesis

Chemical substances (such as HCPC), physical factors (such as X-rays, α-rays, β-rays) can change the genetic information machinery in humans, transforming precancerous genes (Proto-oncogene) into genes cancer (Oncogene = K gene). Viruses put their information into the body, merge with the information of human cells, synthesize DNA according to the viral information code, resulting in the synthesis of viral DNA and RNA in human cells. The mechanism of carcinogenesis can be summarized as follows:

Standard of Tumor marker

Markers for the diagnosis of cancer have some of the following criteria:

Organizationally specific, different from the molecule produced by healthy (normal) cells. Organ specificity, only the organ with cancer.

Ease of collection and preservation of specimens such as plasma and urine. . Has high sensitivity and reflects tumor progression.

It can be detected at low concentrations, so there is the possibility of early detection (early diagnosis) of the disease.

Tumor marker quantification allows monitoring:

Disease progression.

Treatment effectiveness.

Prognosis of the patient's condition.

Advantages of Tumor markers

Specific for cancer (localization).

Tumor marker concentrations are proportional to tumor volume.

Detected at an early stage of the disease.

Accurately determine the concentration of Tumor marker.

Enzyme-immunoassay for Tumor marker determination (Sandwich method)

A marker is an antigen sandwiched between two monoclonal antibodies. The first antibody is attached to the wall of the test tube, the second antibody is attached to a messenger (radioactive isotopes, fluorescent agent or enzyme), so when there is an antigen secreted by K cells in the plasma then the antibody will clamp, forming an antigen-antibody reaction, this KN-KT complex will be detected by a signal emitter: radioactive ray with a radioactive emitter, emitting fluorescent light if The signal generator is a fluorescent substance, if the signal generator is an enzyme, it is determined by the enzyme - color reaction. Usually peroxidase enzyme (POD) is used to decompose H2O2 into H2O and oxygen, this oxygen oxidizes a colorless substance to a colored substance, the color intensity is proportional to the concentration of the KN-KT complex, ie proportional to the concentration. antigens to be determined.

The technique of determining Tumor maker according to this method can be summarized as follows:

Sandwich Method 

1. Solid-phase.

2. Monoclonal antibodies I.

3. Antigen (Tumor Marker).

4. Antibodies II and messengers

(radioactive or fluorescent or enzymatic).

Solid-phase (Streptavidin) - a coating attached to the inside wall of a test tube.

Monoclonal antibody I - attached to the wall of the test tube.

Antigen (Tumor Marker) - present in plasma secreted by K cells, then antibody I binds to the antigen to form an antigen-antibody complex (but not yet detected).

Transmitter-binding antibody II (radioactive, fluorescent, enzymatic) will combine with the appropriate antigen fraction. Thus, 2 antibodies have clamped the antigen in the middle (Sandwich), at this time the antigen-antibody complex thanks to the transmitter can be detected and identified.

Biochemical methods commonly use enzyme transmitters and antigen-antibody detection reactions as follows:

Where: POD is a peroxidase.

After performing the reaction, it is necessary to wash away the excess antibody, leaving only the antinuclear-signaling antibody complex. Currently, the new technique TRACE (time-resolved amplified cryptate emission) does not require an elution phase due to the use of a fluorophore bound to a specific antibody.

Some Tumor Marker to diagnose cancer

You can refer to the Tumor Marker cancer diagnosis below.

Table: Some Tumor markers for cancer diagnosis.

Tumor Marker

Cancer

AFP (Alphafoeto-protein) (Normal < 10 ng/ml)

Liver Cancer

CEA (Carcino- Embronic antigen) (Normal < 10 ng/ml)

Rectal cancer

CA15-3 (Cancer antigen 15-3) (Normal < 30 U/l)

Breast cancer

CA 125 (Cancer Antigen 125) (Normal < 35 U/l)

Ovarian Cancer

CYFRA21-1 (Cytokeratin19 fragment) (Normal < 1.8 ng/ml)

Lung cancer

PSA and FPSA (Prostate specific antigen) Normal: < 50 years old < 1.5 ng/ml

> 50 years old > 5 ng/ml

Prostate cancer

 

CSC (Squamous cell carcinoma) // CYFRA21-1 CA72-

Ear-nose-throat cancer

4 // CA 19- 9, CEA

Stomach cancer

Calcitonin // CEA

Thyroid Cancer

TPA (Tissue polypeptide antigen)

Bladder cancer

CA 19-9 // CEA; SCC // CYFRA21- 1

Stomach cancer

CA 19- 9 // CEA, CA 50

Pancreatic cancer

β-HCG, AFP

Testicular cancer

In the table above the sign // indicates which Tumor marker needs to be combined to determine which organ is cancer.

To identify Tumor markers, people often use biochemical methods: Enzyme-immunoassay (Elisa), in addition, electro-immunoassay (EIA), and radioimmunoassay (RIA) methods are used.