Tumour oxygenation: implications for breast cancer prognosis

Abstract There are areas of limited oxygen availability in most solid tumours, including breast cancer. Hypoxia in solid tumours is mainly a consequence of poor perfusion. Structural and functional abnormalities of newly formed tumour vessels cause spatial and temporal heterogeneity of tissue perfusion. The two principal mediators of hypoxia response, HIF ‐1 and HIF ‐2, are known to be stabilized at different oxygen levels and to have different temporal responses to hypoxia. Recently, stromal HIF ‐1 and HIF ‐2 have been suggested to have opposing roles in breast cancer progression. There is an established link between intralesional, severe hypoxia near areas of necrosis with high levels of HIF ‐1 and poor prognosis in breast cancer. However, the biological effects of moderate hypoxia and the hypoxic response of stromal cells are currently topics of intense investigation.