Prognosis and therapeutic implications for emerging colorectal cancer subtypes

Although colorectal cancer was one of the first solid tumors to be characterized at the molecular level, a consensus biological classification for researchers and clinicians is lacking. Prognosis and therapy are mainly defined on the basis of patient characteristics and histopathological findings, despite studies showing that, according to mutation and gene-expression profiles, the evolution of colorectal cancer differs substantially, probably because of the high heterogeneity of the disease. In this paper we review the original molecular classifications of colorectal cancer, microsatellite and chromosomal unstable tumors, and more recent attempts to characterize the disease by using intrinsic gene expression clustering methods. These have identified at least three subtypes with different hypermutation, proliferation, and epithelial and mesenchymal features. Furthermore, we discuss preliminary data from evaluation of the potential effect of colorectal cancer subtype on prognosis and treatment response. © 2014 Springer Science+Business Media.