Several mathematical models of tumor growth are now commonly used to explain
medical observations and predict cancer evolution based on images. These models
incorporate mechanical laws for tissue compression combined with rules for
nutrients availability which can differ depending on the situation under
consideration, in vivo or in vitro. Numerical solutions exhibit, as expected
from medical observations, a proliferative rim and a necrotic core. However,
their precise profiles are rather complex, both in one and two dimensions.Comment: 25 page
