Recent research suggests that obesity and excess weight can play a prominent role in the incidence and progression of various cancers. Obesity results from an energy imbalance - that is, energy intake that is higher than energy expenditure - could also influence the growth of cancers. Recognizing the impact that current findings on obesity and cancer could have on future cancer prevention and care, the National Cancer policy Forum (NCPF) of the Institute of Medicine (IOM) help a 2-day workshop on "The Role of Obesity in Cancer Survival and Recurrence," in Washington, DC, on October 31 and November 1, 2011. The Role of Obesity in Cancer Survival and Recurrence: Workshop Summary reviews each presenter's latest clinical evidence on the obesity-cancer link and the molecular mechanisms that might explain that link. Clinicians, researchers, cancer survivors, and policy makers also discussed potential interventions to counter the effects of obesity on cancer, and research and policy measures needed to stem the rising tide of cancer mortality predicted by an increasingly overweight and older population worldwide.The Role of Obesity in Cancer Survival and Recurrence: Workshop Summary explores the complex web of molecular mechanisms that underlie the obesity-cancer link, the ways to design future studies to acquire the information needed to guide patient care, what to advise cancer patients about weight loss, diet, exercise, and other measures to reduce their risk of cancer progression or recurrence and policy suggestions related to research, education, and dissemination of the findings on obesity and cancer.