Molecular biology of sporadic colorectal cancer

Abstract Our understanding of the molecular genetics of colorectal cancer has rapidly evolved over the last 30 years, allowing for the development of targeted therapies. Sporadic colorectal cancers evolve through the accumulation of multiple genetic and epigenetic aberrations primarily involving the chromosomal instability and the microsatellite instability pathways. Precursor lesions exist in both pathways (the adenoma and the hyperplastic polyp/sessile serrated lesion, respectively) allowing for the possibility of bowel cancer screening programmes. The molecular alterations in individual colorectal cancers not only provide information on patient prognosis but may also direct therapeutic choices. A comprehensive understanding of the molecular biology of colorectal cancer is becoming increasingly important for patient management. The molecular biology of inherited colorectal cancers is covered extensively in Chapter 1.