The prevalence of overweight and obesity is increasing worldwide and the evidence base for a link between obesity and cancer is growing. Recent research has found that as the body mass index increases by 5 kg/m2, cancer mortality increases by 10%.  Epidemiological studies have associated obesity with a range of cancer types, although the mechanisms by which obesity induces or  promotes tumorigenesis vary by cancer site. These include insulin resistance and resultant chronic hyperinsulinaemia, increased bioavailability of steroid hormones and localized inflammation.  Studies have also reported the effects of weightloss interventions for the reduction of cancer incidence and mortality. This presentation will provide an update of recent research, with a focus on epidemiologic studies on the link between obesity and cancer.  It will review hypothesized mechanisms underlying the relationship between obesity and cancer. High priorities for future research involve additional work on the underlying mechanisms, and trials to examine the effect of lifestyle behaviour change and weight loss interventions on cancer.