  In this paper we study a mathematical model for the growth of nonnecrotic
solid tumor. The tumor is assumed to be radially symmetric and its radius R(t)
is an unknown function of time t as tumor growth, and the model is in the form
of a free boundary problem. The feature of the model is that a Gibbs-Thomson
relation is taken into account, which resulting an interesting phenomenon that
there exist two stationary solutions (depending on the model parameters). The
global existence and uniqueness of solution are established. By denoting c the
ratio of the diffusion time scale to the tumor doubling time scale, we prove
that for sufficiently small c>0, the stationary solution with the larger radius
is asymptotically stable, and the other smaller one is unstable.
