Because of the way solid tumors adapt the body's machinery to bring themselves more oxygen, chemotherapy and radiation may actually contribute to making these tumors stronger. Mark W. Dewhirst, D.V.M., Ph.D., professor of radiation oncology at Duke University Medical Center, and colleagues made this movie to show a tumor's unstable oxygen levels, a pulsation that Dewhirst believes is partially responsible for tumor growth. Such pulsation can trigger an increase in HIF1 (hypoxia-inducible factor 1), which creates a better growth environment for tumor blood vessels. The therapies also drive an increase in HIF1, which cells use to get the oxygen they need by increasing blood vessel growth into the tumor. Phosphorescence imaging was used to image concentration in blood vessels in 2x3 mm regions of a fibrosarcoma (a bone tumor) in a rat. Oxygen measurements were made every 2.5 min for 60-90 min. The movies depict changes in oxygen pressure that are more than 5 mmHg from the immediately preceding image. Red indicates an increase and blue indicates a decrease. Read more in the June 2008 issue of Nature Reviews Cancer.
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