Spatial Moran models I. Stochastic tunneling in the neutral case

We consider a multistage cancer model in which cells are arranged in a d-dimensional integer lattice. Starting with all wild-type cells, we prove results about the distribution of the first time when two neutral mutations have accumulated in some cell in dimensions d.2, extending work done by Komarova [Genetics 166 (2004) 1571.1579] for d=1.