Redox characteristics of tumours compared to normal tissues

3 REDOX CHARACTERISTICS OF TUMOURS COMPARED TO NORMAL TISSUES 

Hypoxia can now be detected and quantified by microelectrodes and the binding of reactive, reduced metabolites of nitroimidazoles, which reflect oxygen levels (because the radical-anion reduction intermediate is oxygen reactive) [30]. A new fibre-optic probe for tissue oxygenation, now available commercially, relies on measurements of emission from a ruthenium probe, which has an oxygen-dependent excited-state lifetime [31]. Acute or fluctuating hypoxia, which has features in common with ischaemia/reperfusion and therefore with myocardial infarction and stroke, can be detected by vascular stains such as bisbenzimidazole intercalators with different fluorescent characteristics. These can be administered intravenously a few minutes apart  

The importance associated with tumour hypoxia stems from the decreased radiosensitivity of hypoxic cells up to three-fold higher radiation doses are required to kill anoxic cells compared to well-oxygenated ones [32]. Cellular proliferation and resistance to cytotoxic drugs may also be influenced by hypoxia. There is now absolutely no question that hypoxic regions frequently occur in common human tumours and that treatment outcome, i.e. survival, is directly related [28]. 

---