Exogenous and endogenous markers of tumour oxygenation status - Definitive markers of tumour hypoxia?

Hypoxia is a physiological abnormality that has been detected in all solid tumours analysed to date. Studies using polarographic needle electrodes have shown an unequivocal link between the extent of tumour hypoxia and poor treatment outcome. The practical limitations of polarographic needle electrodes have warranted investigation into alternative strategies enabling routine assessment of tumour hypoxia in the clinical setting. This review focuses on the clinical evaluation of exogenous and endogenous markers of tumour hypoxia that may fulfil this role.