  We analyze a phase field model for tumor growth consisting of a
Cahn-Hilliard-Brinkman system, ruling the evolution of the tumor mass, coupled
with an advection-reaction-diffusion equation for a chemical species acting as
a nutrient. The main novelty of the paper concerns the discussion of the
existence of weak solutions to the system covering all the meaningful cases for
the nonlinear potentials; in particular,the typical choices given by the
regular, the logarithmic, and the double obstacle potentials are admitted in
our treatise. Compared to previous results related to similar models, we
suggest, instead of the classical no-flux condition, a Dirichlet boundary
condition for the chemical potential appearing in the Cahn-Hilliard-type
equation. Besides, abstract growth conditions for the source terms that may
depend on the solution variables are postulated.
