Science to practice: Son et Lumiere--understanding tumor heterogeneity

Treatment of cancer is often confounded by tumor heterogeneity.Variations in perfusion inhibit drug delivery to all parts of the tumor (1). Differences in oxygen tension (Po2)cause variations in response to radiation therapy (2).Understanding this tumor heterogeneity, which is caused by the interplay between the cancer cell's gene makeup and the tumor's environment (eg, stromal matrix, tissue vascularity),will likely enable improved treatment strategies.Whole-mount studies, in which the excised tumor is fixed or frozen and then sliced into thin sections - with subsequent staining and microscopic examination of the multiple sections—provide much information about tumor heterogeneity but cannot provide information about dynamic events, perfusion, metabolism, or those processes that exist in the tumor in vivo (including Po2). Intravital microscopy(3), in which a tumor or organ is exteriorized or viewed through a window cut in overlying tissue, can provide information on such dynamic processes; however, those studies are limited by scattering and diffusion of light as it penetrates tissue and so can only enable differentiation of surface structures and events.