the cost-effective biomarkers used in the detection of gastric cancer:
1. Carcinoembryonic Antigen (CEA):
Description: CEA is a glycoprotein involved in cell adhesion. Elevated levels can be found in various malignancies, including gastric cancer.
Utility: Commonly used in monitoring treatment response and disease recurrence rather than initial diagnosis due to its moderate sensitivity and specificity.
Cost-Effectiveness: Relatively low cost, widely available.
2. Carbohydrate Antigen 19-9 (CA 19-9):
Description: A tumor-associated antigen often elevated in gastrointestinal cancers.
Utility: Useful as a supplementary marker. It is not specific to gastric cancer but can support diagnosis in conjunction with other markers.
Cost-Effectiveness: Moderately priced, used in conjunction with other diagnostic tests.
3. Carbohydrate Antigen 72-4 (CA 72-4):
Description: Another tumor-associated antigen that can be elevated in gastric cancer.
Utility: Higher sensitivity for gastric cancer compared to CEA and CA 19-9, making it more useful for initial diagnosis.
Cost-Effectiveness: Reasonably cost-effective, particularly useful in combination with other markers.
4. Pepsinogen I and II:
Description: Pepsinogens are precursors to pepsin, a digestive enzyme produced in the stomach. The ratio of Pepsinogen I to Pepsinogen II can indicate atrophic gastritis, a risk factor for gastric cancer.
Utility: Used as a screening tool for gastric cancer risk, particularly in areas with high prevalence.
Cost-Effectiveness: Cost-effective as a screening tool, especially in high-risk populations.
5. Helicobacter pylori Antibodies:
Description: H. pylori infection is a significant risk factor for gastric cancer. Testing for H. pylori antibodies can help identify individuals at increased risk.
Utility: While not a direct marker for cancer, it is important in assessing cancer risk and guiding further diagnostic evaluation.
Cost-Effectiveness: Very cost-effective, widely available, and useful for population screening.
For stomach cancer, biomarker testing includes:
HER2: Cancer cells may contain larger than normal amounts of a protein called HER2.
PD-L1: Cells may contain larger than normal amounts of an immune checkpoint protein called PD-L1.
Microsatellite instability: Cells may have microsatellite instability.
Recent studies have suggested that breath analysis for volatile organic compounds (VOCs), including methane, could be a non-invasive and cost-effective method for detecting gastric cancer. While not a biomarker itself, the presence of this bacterium is a significant risk factor for gastric cancer, and testing for it (e.g., through urea breath test, stool antigen test, or blood test) can be a part of gastric cancer screening.
CEA may be the cheapest marker of gastric cancer, but it certainly does not allow us to make a diagnosis on its own. It may be an alarm bell to which we must add an endoscopic examination which will be the cornerstone of the diagnosis