Cyclic Hypoxia: An Update on Its Characteristics, Methods to Measure It and Biological Implications in Cancer.
Regions of hypoxia occur in most if not all solid cancers. Although the presence of tumor hypoxia is a common occurrence, the levels of hypoxia and proportion of the tumor that are hypoxic vary significantly. Importantly, even within tumors, oxygen levels fluctuate due to changes in red blood cell flux, vascular remodeling and thermoregulation. Together, this leads to cyclic or intermittent hypoxia. Tumor hypoxia predicts for poor patient outcome, in part due to increased resistance to all standard therapies. However, it is less clear how cyclic hypoxia impacts therapy response. Here, we discuss the causes of cyclic hypoxia and, importantly, which imaging modalities are best suited to detecting cyclic vs. chronic hypoxia. In addition, we provide a comparison of the biological response to chronic and cyclic hypoxia, including how the levels of reactive oxygen species and HIF-1 are likely impacted. Together, we highlight the importance of remembering that tumor hypoxia is not a static condition and that the fluctuations in oxygen levels have significant biological consequences.
Duke Scholars
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- 3211 Oncology and carcinogenesis
- 1112 Oncology and Carcinogenesis
Citation
Published In
DOI
ISSN
Publication Date
Volume
Issue
Location
Related Subject Headings
- 3211 Oncology and carcinogenesis
- 1112 Oncology and Carcinogenesis