For decades, elucidate the dynamics of the microenvironment of solid tumors has been considered a major research challenge. The fact is that different therapies have not succeeded to eliminate entirely cancer cells in tumors. This resistance feature to anticancer drugs is often attributed to genetic or even epigenetic causes. Another important, but less appreciated cause of this resistance -a possible manifestation of the former, is the geometrical and physical heterogeneity within the tumor microenvironment that leads to marked gradients in the rate of cell proliferation and to regions of hypoxia and acidity, all of which can influence the sensitivity of the tumor cells to drug treatment. There have been different approaches to overcome this resistance, mainly altering solid tumors' microenvironment, for instance, promoting angiogenesis to help the entrance of drugs. Radiation some times is not an option due to the hypoxia in the tumor deep tissue. On the other hand, these physical and geometrical factors have been identified to be responsible of the unsuccessful drug disperse in tumors in some specific time and spatial scales. In this direction, we present an update of our model of drug transport in solid tumors, that quantifies these factors in terms of space-dependent coefficients of the Fokker-Planck equation. The model follows experiments conducted in the Laboratory of Medical Physics and Molecular Imaging of the National Institute for Cancer (INCan) and the Institute of Physics (IFUNAM).