Diagnosis of colorectal cancer using molecular techniques

Colorectal carcinoma is a leading cause of death among both males and females globally, with the prevalence being higher in developed countries. It maybe hereditary, sporadic or familial. A complex array of molecular and genetic pathways is causal. The Fearon-Vogelstein adenoma-carcinoma multistep model of colorectal carcinoma is one of the best-known carcinogenesis models involving mutations in tumour suppressor genes, loss of function of mismatch repair genes, and gain of function of proto-oncogenes. While the treatment of colorectal carcinoma with target-specific personalized therapies has improved, it is often detected at an advanced stage, thereby decreasing overall survival and disease-free survival of patients post-operatively. Owing to the progression of colorectal carcinoma from benign adenomatous polyps, screening in asymptomatic and high-risk populations is key. Thus, molecular testing has a significant role in detection of these genetic alterations. Molecular markers, apart from being diagnostically important, also help personalize adjuvant therapy as molecular analysis via validated microarray gene expression profiles provides improved recurrence risk determination and median overall survival via targeted therapy to certain genotypes of colorectal carcinoma. This chapter aims at providing insights on the pathogenesis of colorectal carcinoma, traditional and newer diagnostic methodologies, molecular biomarkers and potential treatment strategies for colorectal carcinoma.