In this talk, we present a numerical analysis of the Eyles-King-Styles tumor growth model, a free boundary problem coupling a Poisson equation in the bulk \Omega with a forced mean curvature flow on its boundary \Gamma. Unlike existing evolving surface analyses based on integer-order Sobolev spaces, this bulk-surface coupling requires H^{1/2}-order regularity on \Gamma. We establish a fractional Sobolev framework that admit a rigorous convergence analysis for continuous finite elements of polynomial degree at least three.