Henry S. Kaplan Distinguished Scientist Award Lecture 2007. The remarkable yin and yang of tumour hypoxia.
OBJECTIVE
To honour perhaps the most influential man in the radiation sciences, Henry S. Kaplan, by reviewing the field of tumour hypoxia, one of his many interests.


RESULTS
It was postulated over 50 years ago by Thomlinson and Gray that human solid tumours would contain hypoxic cells and that they would exert a negative influence on the outcome of radiotherapy, a prediction that has been amply validated. In addition to the 'chronic' hypoxia that they proposed we know that tumours also have 'acute' hypoxia produced by the unstable nature of tumour blood flow. The most hypoxic cells in the tumour are the key mediators of the response to large radiation doses (such as are given in stereotactic body radiotherapy), whereas cells at intermediate levels of hypoxia are the most important for standard fractionated radiotherapy. But tumour hypoxia can be exploited to preferentially activate anti-cancer drugs such as tirapazamine in tumours. In addition, hypoxia, through the transcription factor hypoxia inducible factor 1(HIF-1), drives both local angiogenesis and vasculogenesis from circulating cells. We have shown that local tumour irradiation can inhibit angiogenesis, making growth of tumours from surviving cancer cells dependent on vasculogenesis, and that inhibiting key steps in vasculogenesis can markedly sensitize tumours to irradiation.
Brown
Martin
M
Department of Radiation Oncology, Stanford University, California 94305, USA. mbrown@stanford.edu
D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use; D001363:Awards and Prizes; D015687:Cell Hypoxia / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects*; D049673:History, 20th Century; D049674:History, 21st Century; D006801:Humans; D000860:Hypoxia / Q000188:drug therapy / Q000503:physiopathology / Q000532:radiotherapy*; D051793:Hypoxia-Inducible Factor 1 / Q000378:metabolism; D008297:Male; D009369:Neoplasms / Q000188:drug therapy / Q000503:physiopathology / Q000532:radiotherapy*; D009389:Neovascularization, Pathologic / Q000378:metabolism; D018787:Radiation Oncology / Q000266:history / Q000379:methods*; D012108:Research Personnel
D000970:Antineoplastic Agents; D051793:Hypoxia-Inducible Factor 1