International Journal of Clinical Case Reports 2024, Vol.14, No.2, 79-86 http://medscipublisher.com/index.php/ijccr 80 Subsequently, the field of targeted therapy has experienced rapid development, continuously introducing new targeted drugs and treatment methods, providing more treatment options for cancer patients (Li et al., 2019). This study aims to explore the importance and prospects of targeted therapy for specific genetic variations in cancer. By delving into the role of genetic variations in cancer, as well as the principles and applications of targeted therapy, a better understanding of how to improve cancer treatment in the future will be gained. This knowledge will contribute to providing more effective treatment options for patients. 1 Genetic Variations and Cancer 1.1 Common cancer-associated genetic variations Common cancer-associated genetic variations refer to specific gene or genomic changes closely associated with the occurrence and development of cancer. These genetic variations play a crucial role in different types of cancer, profoundly influencing cancer susceptibility, growth, metastasis, and treatment responses BRAF (v-Raf murine sarcoma viral oncogene homolog B) is a common cancer-associated gene, especially in melanoma. The V600E mutation in the BRAF gene is one of the most common genetic variations in melanoma (Figure 1). This mutation activates the MAPK signaling pathway, leading to uncontrolled proliferation of melanoma cells. Targeted drugs against the BRAF V600E mutation, such as Ipilimumab and Vemurafenib, have shown significant therapeutic effects (Goto et al., 2022). Figure 1 V600E mutation of BRAF gene In non-small cell lung cancer, mutations in the epidermal growth factor receptor (EGFR) significantly impact both treatment and prognosis. EGFR mutations can lead to uncontrolled cell growth and differentiation, thereby promoting the development of cancer. Drugs targeting EGFR mutations, such as Gefitinib and Erlotinib, have demonstrated significant efficacy in patients with non-small cell lung cancer. The biological mechanisms of genetic variations refer to the biological processes and molecular mechanisms that lead to changes in genes or the genome. These variations may include single nucleotide polymorphisms, gene mutations, gene rearrangements, chromosomal abnormalities, etc. They can have a broad impact on an individual's genetic information and phenotype. Point mutation refers to a change in one or more nucleotides in the DNA sequence, which may result in the production of a new protein, alteration of protein function, or the appearance of a stop codon. This type of mutation is common in cancer and genetic diseases. For example, base transition mutations may lead to the substitution of one amino acid for another, thereby altering the structure and function of the protein. Gene rearrangement refers to the rearrangement of two or more gene segments on a chromosome, typically playing a crucial role in the development of the immune system. In diseases such as lymphoma and leukemia, gene rearrangement can lead to new combinations of immunoglobulin genes, resulting in abnormal B cells or T cells. Chromosomal abnormalities involve changes in whole chromosomes, chromosome segments, or the number of chromosomes. For instance, Down syndrome, caused by the triplication of chromosome 21, is an example of
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