This session would introduce recent concepts demonstrating the importance of metabolic changes that drive tumor progression and response to treatment. New data on the mechanisms through which metabolic changes in cancer influence the tumor microenvironment, tumor hypoxia, and response to treatment with radiation will be discussed. Conversely, radiotherapy and new, targeted agents influence tumor metabolism in ways that are also important for how tumors respond to therapy. At the conclusion of this activity, the learner will be able to do the following: 1. Explain new concepts in tumor metabolism. 2. Describe the influence of radiotherapy on tumor metabolism. 3. Describe tumor metabolism as therapeutic targets with RT.