Cancer Genetics and Epigenetics, 2025, Vol.13, No.2, 62-76 http://medscipublisher.com/index.php/cge 70 patient, and then a treatment plan suitable only for him/her can be formulated (Derouet et al., 2020). Some people have also thought that checking the DNA floating in the blood (cfDNA) might discover genetic changes that cannot be found in tumor tissues, helping doctors select more appropriate treatments (Pectasides et al., 2018). These personalized treatment methods are designed specifically based on the specific genetic issues of each patient's tumor, aiming to create approaches that are only suitable for him/her, so as to make this difficult-to-treat disease more effective. 9 Case Study 9.1 Detailed analysis of representative cases Jammula et al. (2020) conducted a comprehensive study in 2020 on 150 patients with Barrett's esophagus (BE) and 285 patients with esophageal adenocarcinoma (EAC). Based on the characteristics of DNA methylation, researchers classified these cases into four different types and further analyzed them by combining data on gene expression and gene composition. These types each have unique genetic and "acquired genetic alteration" characteristics, such as excessive DNA methylation in certain regions, special expression patterns of metabolism-related genes, different infiltration conditions of immune cells, and insufficient DNA methylation in some areas accompanied by structural changes. This meticulous classification enables people to have a clearer understanding of the differences between BE and EAC, and also highlights the complexity of these two diseases. 9.2 Genomic map and clinical outcomes Scientists have conducted extensive research on the genetic map of EAC and discovered a lot of important information about the causes of the disease and potential treatment directions from it. For instance, Hoppe et al. discovered in 2021 that genes such as TP53, CDKN2A, KRAS and ERBB2 frequently mutated in patients with EAC (Figure 3). These mutations have led to an increase in the number of gene mutations in patients with EAC, and the gene structure has also become chaotic, increasing the difficulty of targeted therapy. In addition, Frankell et al. identified 77 genes that drive the development of EAC and 21 key components that do not encode proteins in 2018, with an average of 4.4 such key changes occurring in each tumor. The study also pointed out that more than half of EAC patients are sensitive to CDK4 and CDK6 inhibitors, which provides new ideas for targeted therapy. Figure 3 shows the genetic map of EAC, marking the key genes and signaling pathways that promote the development of EAC, such as TP53, CDKN2A and ERBB2. These findings have enabled us to have a deeper understanding of the pathogenesis of EAC and have also laid an important foundation for the development of new treatment methods. Figure 1 is very suitable for demonstrating the genetic characteristics of EAC and its role in disease development. It is recommended to be placed in the chapter introducing the genetic characteristics and clinical applications of EAC. 9.3 Lessons learned and implications for future research Combining the data of genes, gene expression and "acquired genetic alterations" for analysis enables us to have a more comprehensive understanding of BE and EAC. Different types are distinguished based on methylation characteristics (Jammula et al., 2020), which indicates the importance of treating patients according to their individual differences. In addition, the key mutations discovered by Hoppe et al. (2021) and Frankell et al. (2018), as well as the relationship between these mutations and therapeutic effects, provide a basis for the development of targeted drugs. The following research should verify these findings in more diverse patient groups and explore the therapeutic effects targeting specific genetic changes. Moreover, during the course of disease development and after chemotherapy, gene mutations are constantly changing (Murugaesu et al., 2018). This requires long-term follow-up research to observe the changes in genes and identify stable therapeutic targets. Understanding the relationship between the changes in genes themselves and "acquired genetic alterations" is the key to formulating effective treatment plans for BE and EAC.
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