Tissue architecture impacts the evolutionary course of cancer Tumors are genetically diverse with different mutations arising at different times throughout growth and development. Many models have tried to explain how genetic heterogeneity arises and what impact these alterations have on tumor growth. In a new article published in Nature Communications, Moffitt Cancer Center researchers show how the location of the tumor and spatial constraints put on it by the surrounding tissue architecture impact genetic heterogeneity of tumors. Genetic differences are apparent among tumors from different patients, as well as within different regions of the same tumor of an individual patient. Some of these mutations may benefit the tumor and become selected for, such as mutations that allow the tumor to grow faster and spread to other sites. This type of tumor evolution is known as Darwinian evolution.