The CRISPR/Cas9 technique is one of the gene-editing tools. The CRISPR/Cas9 method is favoured by many due to its high degree of adaptability and precision when cutting and pasting DNA. It makes it possible to carry out genetic engineering on an unprecedented scale at a very low cost, which is one of the reasons why it is so popular. It differs from previous methods of genetic engineering in that it permits the addition or deletion of multiple genes simultaneously. Additionally, it is unique in that it is not species-specific, allowing it to be applied to organisms that were previously resistant to genetic engineering. CRISPR/Cas9 has emerged as a potent strategy for altering the genome, and it has been extensively utilized in a variety of cell lines. CRISPR/Cas9 creation of cell and animal models laid the groundwork for the clinical trials that might have treated the tumor. The technology of genome editing through CRISPR-Cas9 holds great promise for preventing tumor migration, invasion, and even treatment. However, its clinical application is constrained by the possibility of an off-target effect, necessitating an effective ethical review. The research and limitations of cancer clinical trials are discussed, as are the molecular mechanisms of CRISPR/Cas9.