Tumor hypoxia

Overview
Tumor hypoxia is the situation where tumor cells have been deprived of oxygen. Hypoxic tumor cells usually resist to radiotherapy and chemotherapy as they can be made more susceptible to treatment by increasing the amount of oxygen in them, but bioreductive prodrugs play a significant part in dealing with this kind of cells: they can kill the oxygen-deficient tumor cells selectively as hypoxic cytotoxins. Study of tumors in such conditions was pioneered by Dr L. H. Gray.

It can also be a result of the high degree of cell proliferation undergone in tumor tissue, causing a higher cell density, and thus taxing the local oxygen supply.