Mechanical forces are increasingly recognized as key regulators of solid-tumour development, including at very early stages. Yet many growth models still treat tumours as bulk volumetric growth, despite evidence that proliferation is localized within a peripheral layer of cells. In this contribution, we present a mechanics-based framework that couples boundary-driven accretion with hyperelasticity to explain the emergence of stress patterns during tumour growth [1]. Newly formed cells are incorporated at the boundary and immediately deformed by the action of the host tissue, generating a frustrated reference configuration and a build-up of residual stress [2]. We quantify how host stiffness modulates growth-induced stresses, highlighting connections between in vitro spheroid mechanics to in vivo constrained growth. Moreover, we also investigate how tissue cutting during tumour surgical removal can affect the stress state within the tumour. [1] Riccobelli D., Surface tension-driven boundary growth in tumour spheroids, Interface Focus, 15(2), 20240035, 2025. [2] Magni F., Noselli G., Riccobelli D., Surface accretion in solid tumors, in preparation, 2026.