ABSTRACT
Rapid advances in molecular biology in the past two decades have uncovered many genetic and molecular alterations in cancer. Based on the newly acquired knowledge, a number of molecularly targeted cancer treatment drugs have been developed that prolong survival, induce remission of tumor, and provide better quality of life for cancer patients. The product of permeability and blood concentration of a solute gives the unidirectional diffusional flux from blood to interstitial space per unit surface area of capillary endothelium. PS is the product of permeability and the total surface area of capillary endothelium in a mass of tissue (usually 100 g of tissue) and hence is the total diffusional flux across all capillaries in that mass. The structural and functional abnormalities of tumor vessels result in regions that are poorly perfused, hypoxic and high in interstitial pH (50). These characteristics of the tumor microenvironment limit the efficacy of many nonsurgical cancer treatments.
