Integrative oncology is an evolving evidence-based specialty that uses complementary therapies in concert with medical treatment to enhance its efficacy, improve symptom control, alleviate patient distress and reduce suffering. In North America the evolution of research into complementary therapies was delayed by the narrow focus of the Flexner Report. A government-funded research agenda and incorporation of complementary therapies into medical school curricula have been driven by early evidence of efficacy and patient demand. Integrative oncology focuses on the role of natural health products (botanicals, vitamins, and minerals), nutrition, acupuncture, meditation and other mind-body approaches, music therapy, touch therapies, fitness therapies, and more. Some natural health products, such as herbs and their constituent phytochemicals, may be biologic response modifiers that could increase cancer control. Current research stretches from the laboratory to health services. Institutions are exploring the effectiveness gap in their clinical services and are determining efficacy of complementary therapies through randomized controlled trials. Eventually, the goal is to establish practice guidelines through determining relative effectiveness and value through cost-utility studies. The aim of integrative oncology should be one medicine, not alternative; it should be patient-focused; it should be evidence-based; and it should provide the best care for cancer cure, prevention, symptom control, and quality of life.