Genetics, screening, and chemoprevention

The last few decades have seen tremendous advances in the understanding of human genetics, especially since the sequencing of the human genome in 2003. With rectal cancer, as with all cancers, genetics is at the center of its etiology, whether it is associated with an inherited syndrome or a somatic mutation from environmental or other oncogenic factors. Understanding the genetics of cancer has improved the understanding of all aspects of oncology and cancer biology, such as cancer progression and spread, cancer prevention, and cancer treatment, especially considering “personalized medicine” that allows an individual’s cancer “genetic signature” to be used to tailor therapy. Unlike the surgical treatment of rectal cancer addressed in this textbook, there is little unique to rectal cancer relative to colon cancer when discussing cancer genetics and cancer biology. Instead, most of the research and advances in this field have focused on both colon rectal cancer (CRC) based on their indistinguishable genetic signature [1], and therefore this chapter will focus on the genetics of CRC with particular attention to the impact of genetics on cancer development as well as cancer outcomes and chemotherapeutic treatment. Additionally, CRC screening and chemoprevention options, critical for early detection and prevention efforts and also not often specific to rectal cancer, will be addressed.