Cancer as a tool for preclinical psychoneuroimmunology

Cancer represents a novel homeostatic challenge to the host system. How the brain senses and responds to changes in peripheral physiology elicited by tumor growth is a largely untapped area of research. This is especially relevant given the widespread prevalence of systemic problems that people with various types of cancer experience. These include disruptions in sleep/wake cycles, cognitive function, depression, and changes in appetite/food intake, among others. Critically, many of these problems are evident prior to diagnosis, indicating that their etiology is potentially distinct from the effects of cancer treatment or the stress of a cancer diagnosis. Psychoneuroimmunology (PNI) is well equipped to tackle these types of problems, as it uses approaches from multiple disciplines to understand how specific stimuli (endogenous and environmental) are transduced into neural, endocrine, and immune signals that ultimately regulate health and behavior. In this article, I first provide a brief historical perspective of cancer and PNI, introduce the idea of cancer as a systemic homeostatic challenge, and provide examples from preclinical literature supporting this hypothesis. Given the rise of advanced tools in neuroscience (e.g., calcium imaging), we can now monitor and manipulate genetically defined neural circuits over the extended time scales necessary to disentangle distal communication between peripheral tumors and the brai