Cell proliferation and cell diffusion seem to be important quantities to estimate when trying to understand or measure tumor growth, but I don't really understand a) the difference between them or b) their relationship to tumor growth.
Cell proliferation refers to cellular subdivision. This doesn't necessarily mean tumor growth because something can subdivide but still have the same net mass, right?
Cell diffusion on the other hand, refers to changes in cell density. Supposing cell proliferation is constant and we have positive diffusion, that would mean that cells are 'spreading out' (ie the mass is less dense but bigger). Is this correct? Would positive diffusion be equivalent to tumor growth?
This question came up when reading this paper. It talks about estimating diffusion and proliferation parameters in order to solve the reaction-diffusion equation which is, in turn, used to model tumor growth.