white blood cells and cancer cells transport through lymphatic vessels
The "valves" are basically one way valves that just prevent backflow of interstitial fluid from the lymph into the interstitial space, so they do not specifically affect the flux of WBCs, cancer cells, etc. into the lymph vessels. In terms of a mathematical model of flux into the lymph vessels, you could use Poiseuille's law to determine the flow rate of interstitial fluid through the "valves", then multiply by the concentration of WBCs, etc. in the interstitial fluid to get the flux of the given cells into the lymph vessels. Of course, that is just one possible model for one parameter (cell flux).