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The Clinical Significance of Tumor Marker Detection (I)

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In recent years, the incidence of cancer patients has been increasing yearly. Tumor markers have become mandatory items in many human examination projects. Among so many tumor indicators, how to identify their clinical significance? Let’s learn about the clinical significance of tumor marker detection in this article.

Tumor markers are a class of substances that are synthesized or released by tumor cells themselves or generated or elevated by the body's response to tumor cells. Tumor markers are present in blood, cells, tissues or body fluids, reflecting the presence and growth of tumors. Tumor markers are determined by methods such as chemistry, immunology, and genomics, for tumor diagnosis, curative effect and recurrence monitoring, and prognosis judgment Has a certain value. Tumor markers mainly include protein, sugar, enzyme and hormone tumor markers.

  1. Protein tumor markers

1.1 Alpha-fetoprotein (AFP) determination

Alpha-fetoprotein is a serum glycoprotein synthesized early in the fetus. After birth, AFP synthesis is inhibited. When malignant lesions occur in liver cells or gonad embryo tissues, cells capable of synthesizing AFP restart to synthesize, resulting in a marked increase in blood AFP content. Therefore, the detection of AFP concentration has important clinical value for the diagnosis of hepatocellular carcinoma and trophoblastic malignant tumors.

Reference value: <25μg/L

Clinical significance:

  • Primary liver cancer;
  • Gonad embryo tumor;
  • Viral hepatitis and cirrhosis (usually <300μg/L).

1.2 Carcinoembryonic Antigen (CEA) determination

The CEA content in the body after birth is extremely low and it is a broad-spectrum tumor marker that can be expressed in a variety of tumors. It is mainly used to assist the diagnosis, prognosis, curative effect monitoring and tumor recurrence of malignant tumors.

Reference value: <5μg/L

Clinical significance:

  • Increased CEA is mainly seen in patients with pancreatic cancer, intestinal cancer, gastric cancer, lung cancer, etc;
  • The concentration decreases when the dynamic observation improves, and vice versa;
  • CEA increased slightly in smoking patients.

1.3 Tissue peptide antigen (TPA) determination

The level of TPA in the blood is closely related to the degree of cell division and proliferation. The higher the level of TPA in the serum, the more commonly used clinically for the auxiliary diagnosis of rapidly proliferating malignant tumors, especially for monitoring the efficacy of known tumors.

Reference value: 130U/L

Clinical significance:

  • The serum TPA level of patients with malignant tumors can be significantly increased;
  • TPA level decreases after improvement, if it rises again, it indicates relapse;
  • The simultaneous detection of TPA and CEA is conducive to the differential diagnosis of malignant and non-malignant breast tumors.

1.4 Prostate specific antigen (PSA) determination

In prostate cancer, serum PSA levels are elevated. 80% of total serum PSA (t-PSA) exists in bound form, called composite PSA (c-PSA); 20% exists in free form, called free PSA (f-PSA). t-PSA and f-PSA increased, while the ratio of f-PSA/t-PSA decreased, suggesting prostate cancer.

Reference:

t-PSA<4.0μg/L

f-PSA<0.8μg/L

f-PSA/t-PSA>0.25

Clinical significance:

  • Prostate cancer;
  • If the concentration of t-PSA does not decrease or rises again after prostate cancer resection, it indicates tumor metastasis or recurrence;
  • PSA will increase after anal finger examination, prostate massage, and cystoscopy.

1.5 Squamous cell carcinoma antigen (SCC) determination

SCC is a subtype of tumor-associated antigen TA-4, a glycoprotein

Reference value: <1.5μg/L

Clinical significance:

  • Lung squamous cell carcinoma, cervical cancer, esophageal cancer;
  • Some benign diseases such as psoriasis and other skin diseases, renal insufficiency, upper respiratory tract infections, etc. can also cause increased SCC concentration;
  • Contamination of sweat, saliva and other body fluids can cause false positives.

1.6 Cytokeratin 19 fragment (CYFRA 21-1) determination

Mainly distributed in tissues or organs rich in epithelial cells, such as lung, breast, bladder, intestine, etc. When these tissues become malignant, the level of CYFRA 21-1 in the blood can be seen to increase. At present, it is mainly used for differential diagnosis and prognosis evaluation of non-small cell lung cancer.

Reference value <2μg/L

Clinical significance:

  • It is the preferred tumor marker for non-small cell lung cancer;
  • In addition to lung cancer, YFRA 21-1 increased in breast cancer, bladder cancer, colorectal cancer, etc.;
  • Other benign diseases such as pneumonia, tuberculosis, gastrointestinal diseases, etc., but their levels are slightly elevated (generally <10μg/L).
  1. Glycolipid tumor markers

2.1 Cancer Antigen 50 (CA50)

It is a tumor carbohydrate antigen and has no organ specificity for tumor diagnosis.

Reference value <20,000 U/L

Clinical significance:

  • Increased pancreatic cancer, gallbladder (tract) cancer, primary liver cancer, etc.;
  • Dynamic observation of its level is of great value for the prognosis of cancer tumors and judgment of recurrence monitoring;
  • It is valuable to distinguish benign and malignant pleural and abdominal effusions;
  • In chronic liver disease, pancreatitis, and bile duct disease, CA50 also increases.

2.2 Cancer Antigen 724 (CA724)

CA724 is a tumor-associated glycoprotein, which is a marker of gastrointestinal and ovarian cancer.

Reference value<6.7μg/L

Clinical significance:

  • The increase is seen in ovarian cancer, colorectal cancer, gastric cancer, pancreatic cancer;
  • Joint detection with CA125 can improve the detection rate of ovarian cancer;
  • Joint detection with CEA can improve the sensitivity and specificity of gastric cancer.

2.3 Sugar chain antigen 199 (CA199)

CA199 is a glycoprotein. Normal human salivary glands, prostate, pancreas, breast and other epithelial cells have a small amount of CA199.

Reference value <37,000 U/L

Clinical significance:

  • The preferred tumor marker for pancreatic cancer;
  • Can be found in acute pancreatitis, acute hepatitis, gallbladder cancer, cholangiocarcinoma, gastric cancer, colon cancer, etc.;
  • Continuous detection is of great value to the progression of the disease, surgical efficacy, prognosis estimation and diagnosis of recurrence;
  • Combined with CEA detection to improve the diagnosis rate of gastric cancer.

To be continued in Part II…


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