The first genetically engineered mouse model (GEMM) dates back to the 1970s, but GEMMs are still used today to develop our understanding of human diseases and cancers [1]. Mouse models have provided insights into the initiation, progression and spread of cancer with the eventual goal of informing approaches to treatment and clinical care. Some of the most celebrated and widely used models in the field have been applied to the study of high-incidence human cancers. Oncomice, including the MMTV-PyMT (polyomavirus middle T antigen) mouse, TRAMP (transgenic adenocarcinoma mouse prostate) mouse and APCMin (multiple intestinal neoplasm mutation of APC gene) mouse, have been used to investigate breast, prostate and intestinal cancers, respectively [[2], [3], [4], [5], [6]]. While these GEMMs have transformed our understanding of tumourigenesis, experts disagree over the utility of these preclinical models with regard to patient care, and question if mouse models can accurately predict human responses to novel anti-cancer drugs or immunotherapies. We will review and compare the fundamental findings from three widely used murine models (APCMin, MMTV-pYMT, TRAMP) and discuss their impact on clinical care and human disease.