Novel targets for drug development

Abstract Colorectal cancer is a highly heterogeneous disease that comprises different tumour phenotypes, characterized by specific molecular and morphological alterations. These have been categorized by a number of different systems, which have some similar and some more diverse descriptions. The systems are being refined all the time, as we develop a greater understanding of the pathways involved. The importance of the subtypes is underscored by the fact that they respond differently to different anti-cancer agents and therefore, by understanding their genesis, further novel agents can be developed specifically to target a single molecular subtype leading to increased personalization of cancer medicine and better outcomes.