Insights from a novel tumor model: Indications for a quantitative link between tumor growth and invasion.

Both the lack of nutrient supply and rising mechanical stress exerted by the microenvironment appear to be able to cause discrepancies between the actual, observed tumor mass and that predicted by West et al.'s [A general model for ontogenetic growth. Nature 2001;413:628-31] universal growth model. Using our previously developed model we hypothesize here, that (1) solid tumor growth and cell invasion are linked, not only qualitatively but also quantitatively, that (2) the onset of invasion marks the time point when the tumor's cell density reaches a compaction maximum, and that (3) tumor cell invasion, reduction of mechanical confinement and angiogenesis can all contribute to an increase in the actual tumor mass m towards the level m(W) predicted by West et al.'s universal growth curve. These novel insights contribute to our understanding of tumorigenesis and thus may have important implications not only for experimental cancer research but also be of value for clinical purposes such as for predictions of tumor growth dynamics and treatment impact.