The Wnt-β-catenin signalling pathway plays a crucial role in the regulation, differentiation, proliferation and cellular death processes; consequently, alterations in this pathway are involved in numerous abnormalities of development, growth and homeostasis in animal organisms. Wnt proteins include a numerous family of secretion glycoproteins which join to Frizzled receptors and Low Density Lipoprotein Receptor-related Protein, in order to stabilize the critical β-catenin protein, and to initiate an intricate signaling cascade, which is related to multiple nucleocytoplasmatic processes. Alterations in the canonical Wnt-β-catenin signaling pathway have been associated with variations in a number of proteins participating in this route, or with activation / inactivation of oncogenes and tumor suppressor genes, which explain different processes of tumorigenesis, in addition to a number of malformations and human diseases. This review describes the relations between the Wnt-β-catenin signaling pathway with different neoplasic processes, as well as its application in the diagnosis and prognosis of cancer.