Mechanics of growth of a viscoelastic tumor

In this work, tumor growth in living tissues is discussed using a model of mechanics of continuous media. Growing living tissue is considered as a viscoelastic body, and tumor enlargement is assumed to be the mass increase of particles that make up the tissue. The theory of multiple natural configurations occupies an important place at the basis of the problem. In this theory, the development of a tumor is divided into two parts that are different from each other. The first is the volumetrically growth where the change in mass is assumed. The second is the response of the material in which the stress change is considered. It is assumed that tumor growth is due to nutrients soluble in the interstitial fluid. The two examples are studied on the resulting formulation. The first one is the homogeneous and isotropic growth of a linear viscoelastic body in a rigid cylinder. This example is considered for bronchial tumors in human lungs. The second is the inhomogeneous, isotropic and free growth of a linear viscoelastic sphere, and this model is discussed for the human lung tumors. The obtained results are depicted with graphics.