An individual’s subjective appraisal of the experiences of cancer and its treatment is an important factor in whether he or she develops a stress response syndrome or experiences posttraumatic growth. Posttraumatic stress disorder, broadly defined by the U.S. National Institute of Mental Health as “an anxiety disorder that can develop after exposure to a terrifying event or ordeal in which grave physical harm occurred or was threatened,” is the most commonly described stress response, with acute stress disorder and subthreshold or partial posttraumatic stress disorder also occurring. This evidence-based review article addresses the definitions, prevalence, contributing factors, risk factors and protective factors, as well as the clinical management of stress response syndromes in cancer patients. The article also describes the posttraumatic growth experienced by many patients, and outlines some changes in care that have been promoted by the cancer survivorship movement. Clinical examples illustrate some typical presentations of people confronting the adaptive challenges associated with the cancer trajectory.