Medical professionals, scientists, and patients have long grappled with the dubious nature of medical certainty regarding diagnosis, treatment, and prognosis of disease states. Constructing certainty requires reductions and deductions. It requires us to take what we know now and make best guesses about what will be. We try to make peace with medical uncertainty by monitoring symptoms, modeling risk, and looking toward evidence. But bodies in flux always outpace the human gaze. With research, technologies, and patients themselves constantly changing, how do practitioners ultimately make decisions about care?Bodies in Flux looks at the many ways humans coproduce medical knowledge. Each chapter investigates one specific scientific method for negotiating medical uncertainty in cancer care, including evidential visualization, assessment, synthesis, and computation. The cases pull back the curtain to show doctors deliberating over the best ways to treat a patient, the FDA holding drug hearings to decide dosage, researchers synthesizing studies into evidence-based standards, and pharmaceutical companies designing genetic tests for consumers. Teston concludes by advocating for an ethic of care that embraces human bodies' flux and frailty.