Quantitative Spatial Analysis of Hypoxia and Vascular Perfusion in Tumor Sections

Abstract

The presence of tumor hypoxia is associated with poor patient outcome to cancer treatment, including radiation therapy and surgery. Hypoxia itself may indicate a more aggressive tumor phenotype, and tumor hypoxia has been associated with the probability of metastatic development. Numerous methods are available to quantify hypoxia, including polarographic needle probes (e.g., Eppendorf p02 histograph), fluorescence-based needle probes (e.g., OxyLite), the comet assay, and nitroimidazole-based hypoxia markers (e.g., pimonidazole, NITP, EF3, and EF5). A unique feature of hypoxia markers is that they permit the investigation of not only tumor-averaged hypoxia, but also the spatial distribution of oxygen within the biopsies sampled. Such data facilitate the investigation of the effects of intratumoral oxygen distribution on the microregional response to oxygen-dependent treatment modalities. For example, knowledge of the spatial distribution of oxygen is important in Photodynamic Therapy (PDT), which may target vascular-distant tumor cells, as well as the vascular endothelium itself. The present manuscript describes a Matlab-based image-processing program that we have developed for the quantitative analysis of the spatial distribution of tumor hypoxia, as labeled by the hypoxia markers EF3 or EF5.