2. Molecular biology of colorectal cancer

An estimated one million people in the world are diagnosed each year with CRC cancer. Over 30% of these people will die of disseminated disease. In recent years, we have furthered our knowledge of the molecular mechanisms responsible for the onset, development, and spread of the disease to other organs. The Vogelstein model of CRC tumorigenesis, published in the early 1990s, pioneered our understanding of how solid tumours developed. Major advances in the field of tumour neoangiogenesis and greater knowledge of the function of epidermal growth-factor receptors have since added new specifically targeted drugs, such as bevacizumab, cetuximab, and panitumumab, to the armamentarium. Moreover, we know that certain changes in the intracellular signalling cascade triggered by these receptors can influence drug response. In this chapter we summarise our knowledge of tumour-cell physiology itself, the microenvironment surrounding colon cancer, and the possible involvement of epigenetic phenomena and stem cells in the genesis and development of these tumours.