Cancer Genetics and Epigenetics 2024, Vol.12, No.4, 194-209 http://medscipublisher.com/index.php/cge 195 Additionally, the study aims to address the challenges and limitations associated with using non-invasive biomarkers and proposes future research directions. By achieving these goals, it provides a comprehensive understanding of the role of non-invasive biomarkers in CRC, emphasizing their potential to transform current diagnostic practices and improve patient outcomes. 2 Overview of Colon Cancer Colon cancer, a subtype of colorectal cancer (CRC), is a major health concern worldwide due to its high prevalence and mortality rates. It is the third most commonly diagnosed cancer and the second leading cause of cancer-related deaths globally. Understanding the pathophysiology, epidemiology, and current diagnostic techniques of colon cancer is crucial for developing effective prevention, diagnosis, and treatment strategies. 2.1 Pathology and epidemiology Colon cancer typically develops from adenomatous polyps, which are benign growths on the inner lining of the colon that can transform into malignant tumors over time. The pathogenesis of colon cancer involves a series of genetic and epigenetic alterations that lead to the uncontrolled growth of colonic epithelial cells. Key genetic changes include mutations in the APC gene, KRAS gene, and p53 tumor suppressor gene, as well as microsatellite instability and chromosomal instability (Dalerba et al., 2016). Epidemiologically, colon cancer exhibits significant variations in incidence and mortality based on geographical regions, age, gender, and lifestyle factors. Developed countries report higher incidences, which are attributed to dietary habits, sedentary lifestyle, and aging populations. In contrast, developing countries are experiencing a rise in cases due to the adoption of Western lifestyles. The disease is more common in individuals over 50 years old, with men being slightly more affected than women (Leijssen et al., 2018). Familial and hereditary syndromes, such as Lynch syndrome and familial adenomatous polyposis, also play significant roles in the risk of developing colon cancer. 2.2 Current diagnostic techniques and their limitations The gold standard for colon cancer diagnosis is colonoscopy, which allows for direct visualization and biopsy of colonic lesions. Colonoscopy is highly effective but is invasive, costly, and uncomfortable for patients, which can lead to lower compliance rates in screening programs. Other diagnostic methods include the fecal occult blood test (FOBT) and fecal immunochemical test (FIT), which are non-invasive tests that detect hidden blood in stool samples, potentially indicating the presence of tumors. However, these tests have limited sensitivity and specificity, particularly for detecting early-stage cancers (Riihimäki et al., 2016). Sigmoidoscopy, a less invasive alternative to colonoscopy, examines only the distal part of the colon but misses proximal lesions. CT colonography, also known as virtual colonoscopy, provides a detailed view of the colon but requires bowel preparation and has lower sensitivity for detecting small polyps compared to colonoscopy (Hunter et al., 2017). Despite these diagnostic tools, early detection of colon cancer remains challenging due to the asymptomatic nature of early-stage disease and the limitations of current screening methods in terms of accuracy, invasiveness, and patient compliance. 2.3 Need for non-invasive diagnostic methods Given the limitations of current diagnostic techniques, there is a pressing need for non-invasive diagnostic methods that are accurate, cost-effective, and patient-friendly. Non-invasive biomarkers offer a promising solution. These biomarkers can be detected in easily accessible body fluids such as blood, stool, and urine, providing a less invasive means to screen and diagnose colon cancer. Non-invasive biomarkers can enhance early detection, improve patient compliance with screening programs, and reduce healthcare costs. They include circulating tumor DNA (ctDNA), which consists of fragments of DNA shed by tumors into the bloodstream that can provide information about genetic mutations and tumor burden. MicroRNAs (miRNAs), small non-coding RNAs that regulate gene expression, are also dysregulated in colon cancer and can serve as diagnostic and prognostic markers (Karim et al., 2017). Additionally, specific protein
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