Cancer, a malignant pathology characterized by accelerated and uncontrolled cellular proliferation, is the leading cause of death worldwide. Several experimental and theoretical efforts have been taken to unravel the mechanism of tumor development and metastasis establishment. Constitutive models, one of these approaches, can characterize mass change and stress development during tumor growth. Solid tumors are hyperelastic, compressible, anisotropic materials with a space and time-dependent behavior, whose mass varies over time. Tumor mass increase is a complex phenomenon, influenced by molecular and genetic factors, cell interactions, vascularization, and mechanical cues. The main goal of this work is to provide a numerical framework to incorporate the effect of mechanical strain in tumor growth. Under the rationale that proliferation is improved in post-stretched cells [1], a constitutive model for the strain-driven growth of a mass (considering the multiplicative decomposition of the deformation gradient into an elastic and a growth contribution) is developed and implemented in Abaqus® using a user-defined subroutine. The model is initially tested using different deformation modes applied to a single unitary hexahedral finite element to validate the numerical solution, quadratic convergence and model objectivity. Then, a rectangular specimen, formed by a solid tumor (with a preferential growth direction) surrounded by softer tissue, is subjected to cyclic stretch scenarios. Finally, ductal carcinoma in situ (DCIS), a pre-invasive form of breast cancer, is considered as a case study. In this example, tumor growth occurs in an anisotropic manner (in the direction of least resistance) influenced by mechanical stimulation (introduced by the contractile myoepithelial cell layer surrounding the duct). These examples demonstrate the potential of the numerical framework to model the role of mechanical strain in tumor growth. With an experimentally derived growth evolution law, this might be an important tool to look at tumor growth as mechano-chemo-biological process. REFERENCES [1] Wang Y, Goliwas KF, Severino PE, Hough KP, Van Vessem D, Wang H, et al. Mechanical strain induces phenotypic changes in breast cancer cells and promotes immunosuppression in the tumor microenvironment. Laboratory Investigation 2020;100.