Tumor hypoxia is important in radiotherapy, but how should we measure it?
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Cell Hypoxia↗
Biomedical subjects
Quynh-Thu Le
Publications and source records attributed to Quynh-Thu Le.
The effectiveness of breath-holding to stabilize lung and pancreas tumors during radiosurgery.
PURPOSE: To evaluate the effect of breath-holding on the short-term reproducibility and long-term variability of tumor position during image-guided radiosurgery. METHOD: Thirteen patients have undergone single-fraction radiosurgery treatments during which the tumor was repeatedly imaged radiographically to observe its position. The imaging data were used to monitor the efficacy of breath-holding and to periodically readjust the alignment of the treatment beam with the tumor. These measurements have allowed the effects of breathing, heartbeat, patient movement, and instrumental uncertainties to be separately identified in the record of tumor position. RESULTS: During inspiration breath-holding, the lung tumor position was reproducible to within 1 mm, on average, in the direction of maximum displacement during regular breathing, and to within 1.8 mm in three dimensions overall. The pancreas tumor position in three dimensions was reproducible to within 2.5 mm on average. Some patients showed a slow, steady drift of tumor position during the extended sequence of breath-holds, which was compensated by periodic retargeting of the treatment beam. CONCLUSION: Breath-holding can allow the reduction of tumor motion dosimetry margins to 2 mm or less for lung cancer treatments, provided that the treatment system can detect and adapt to long-term variations in the mean tumor position during a lengthy treatment fraction.
Humans↗
Hypoxic gene expression and metastasis.
Solid tumors possess malformed vasculature that results in the exposure of tumor cells to a low oxygen environment. Tumor hypoxia has been demonstrated in human and mouse tumors through the use of oxygen microelectrodes, hypoxic specific biomarkers, specific transcriptional changes induced by hypoxia, and secreted proteins. While many elegant experiments have demonstrated that hypoxia enhances metastatic potential, it is still unknown what mechanisms are involved in this enhancement. In this review, we discuss the clinical and basic science studies that support an important role for hypoxia in increasing the metastatic potential of tumor cells by promoting tissue remodeling, inducing angiogenesis and reducing apoptosis. Particular emphasis is given to recent findings that provide insight to the role of hypoxia in the metastatic process.
Animals↗