Stephen T. Sonis, DMD, DMSc received his DMD from Tufts University, and then entered a combined doctorate and clinical specialty training program at Harvard University. Following completion of his degree and residency, he was awarded a Knox Fellowship to study tumor immunology at Oxford University, UK. He returned to the United States to accept joint positions at the Peter Bent Brigham Hospital, Sidney Farber Cancer Center, and the Harvard School of Dental Medicine. Dr. Sonis’ research converged on studies to define the biology and clinical significance of cancer regimen-related mucosal toxicities. The results of his studies on the molecular and cellular pathogenesis of mucositis have established the basis of a mechanistic paradigm for epithelial injury, and have provided treatment targets for biological and pharmaceutical development. Recognizing that genetics play a role in patient risk for mucositis and other toxicities, Dr. Sonis and his collaborators have identified specific canonical pathways that are critical in toxicity development and have used these to form the basis for models of gene-based risk prediction. With the application of network theory to cancer-related toxicities, Dr. Sonis and his colleagues have built on earlier work to define specific toxicity constellations in patients receiving chemotherapy. Dr. Sonis has broad experience in clinical trial design, implementation, and endpoint quality management. Many of his former students and residents now hold academic and clinical leadership positions. Dr. Sonis has published extensively on the clinical, biological, and health economic aspects of cancer and complications associated with its treatment. He is the author of over 200 original publications, reviews and chapters, 7 books, and 5 patents. He has lectured extensively on the clinical and biological aspects of cancer regimen-related toxicities and cancer diagnostics. Dr. Sonis serves on a number of editorial boards, and is a founding member of the International Society of Oral Oncology and the International Academy of Oral Oncology.