Assessment of tumor tissue oxygenation: agents, methods and clinical significance

Hypoxia is a pathophysiological aspect that is characteristic for many solid tumors. It is an indicator for tumor aggressiveness and predicts poor treatment outcome. Thus, the assessment of tumor hypoxia would help clinicians to select patients for additional or more specific treatment regimens. Tumor hypoxia can be detected by invasive and noninvasive techniques. The polarographic oxygen electrode method is considered indispensable to establish the effect of antitumor therapy on hypoxia but its invasive nature prevents frequent and repeated use. Therefore, the development of noninvasive techniques is needed and has been directed towards magnetic resonance imaging (MRI) and scintigraphic imaging. Whereas MRI, though promising, is still in its infancy, scintigraphy has demonstrated its ability to depict hypoxic tumor areas. This paper reviews the state-of-the-art in this field. In addition, this paper mentions the related research and new agents to target hypoxia-related makers to interfere with tumor survival and growth.