Cancer Genetics and Epigenetics 2024, Vol.12, No.1, 37-46 http://www.medscipublisher.com/index.php/cge 40 2.3 Current clinical applications and limitations of molecular markers in gastric cancer The application of molecular markers in the early diagnosis of gastric cancer is gradually becoming an integral part of clinical practice. For instance, the detection of the HER2/neu protein has become a crucial determinant in the treatment planning for gastric cancer patients. If tumor cells from a patient overexpress HER2/neu, they may benefit from targeted therapies against HER2/neu. However, the clinical application of molecular markers still faces several challenges. Firstly, the specificity and sensitivity of many molecular markers may not be sufficient to serve as independent diagnostic tools. For example, certain markers may be expressed in other types of cancers or non-cancerous diseases, leading to diagnostic errors. Secondly, the detection methods for molecular markers often require specialized laboratory equipment and technical personnel, which may be challenging to implement in resource-limited regions. Additionally, the relatively high cost of molecular marker detection may restrict its widespread use in clinical applications. Finally, more clinical research is needed to confirm the long-term efficacy and safety of molecular markers in the early diagnosis of gastric cancer. 3 Genomics and Proteomics Technologies 3.1 Application of genomics in early diagnosis of gastric cancer Genomics is the study of all genes in an organism or tissue, encompassing their interactions and the impact of the environment. In the early diagnosis of gastric cancer, genomics technologies have become a critical tool. They enable researchers to understand the molecular mechanisms underlying the development of gastric cancer at the genomic level, thereby contributing to early detection and treatment. The occurrence of gastric cancer is closely associated with various genetic alterations. For instance, certain hereditary gastric cancers are linked to mutations in the E-cadherin (CDH1) gene (Wang et al., 2022), while the majority of sporadic gastric cancers are associated with abnormal expression of multiple genes. Genomics technologies, such as whole-genome sequencing (WGS), whole-exome sequencing (WES), and high-throughput mRNA sequencing, have been employed to identify key genetic changes in gastric cancer. By comparing the genomes of normal and cancerous tissues, researchers can identify crucial mutations that may contribute to the development of gastric cancer. Moreover, genomic research has revealed the heterogeneity of gastric cancer. Different types of gastric cancer (such as intestinal and diffuse types) exhibit distinct patterns of genetic alterations. This molecular-level differentiation helps guide more personalized treatment approaches. For example, for patients with HER2-positive gastric cancer, targeted therapies against HER2 may be more effective. Despite the enormous potential of genomics technologies in the early diagnosis of gastric cancer, challenges exist. The genetic variations in gastric cancer are highly complex, and many mutations may not be directly causative. Therefore, determining which genetic variations are directly associated with the occurrence of gastric cancer remains a significant research topic. 3.2 Role of proteomics technologies in identifying new biomarkers Proteomics is the scientific study of the expression, function, and interactions of all proteins within cells or organisms. In the diagnosis of gastric cancer, proteomics technologies are particularly crucial because the abnormal expression and modifications of proteins are often direct outcomes of cancer development. Through proteomics technologies such as two-dimensional electrophoresis and mass spectrometry analysis, researchers can identify and quantify protein differences between cancer cells and normal cells (Liu et al., 2020). These differences contribute to the discovery of potential gastric cancer biomarkers that can be used for early diagnosis and treatment monitoring. For example, the expression levels of specific proteins, such as glycoproteins, may significantly differ in gastric cancer cells compared to normal cells. Furthermore, proteomics research can unveil the molecular mechanisms underlying gastric cancer development. By comparing the protein expression profiles of gastric cancer cells at different stages, key proteins and signaling
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