After a brief review of the essentials of gastrointestinal (GI) sensory-motor function and its underlying neuroscience, this chapter highlights the multifaceted pathophysiology that leads to symptoms and altered health-related quality of life. We then provide some examples of possible pharmacologic interventions that a cancer neurogastroenterologist may offer as needed. This is followed by a brief review of the nature and location of precancer, cancer, and post-cancer states that will be deliberated further in this book. Neurogastrointestinal dysfunction may be direct, from a GI focus (i.e., esophageal, gastric, small intestinal, colonic), multiregional, or indirect (primary or secondary), from an extra-intestinal origin of the tumor.