"Several studies have linked the use of insulins to the risk of cancer, and it is certainly plausible that as a growth factor, exposure to administered insulin could stimulate neoplastic growth. However, the meta-analyses of randomized clinical trials comparing different insulin analogues were too small to quantify the risks, especially the proportion of patients that were followed for more than 6 months. Hence, the European Medicines Agency has requested urgent research to determine the risks of cancer for users of insulin and insulin analogues, and investigate possible mechanisms of cancer promotion.CARING will obtain precise data on the incidence of cancer in diabetic patients and determine any link with use of various insulin and insulin analogues. The study will utilise high quality prescription databases and other national datasources, integrated at European level with advanced methods of harmonising data. The study will take into account potential confounders. The project aims to determine the influence of drug dose on risk, and through a risk model, identify predictors of cancer for insulin users. A review of published evidence combined with a study of tumour characteristics and gene expression in breast cancer tumour collections will aid understanding of potential mechanisms of cancer initiation and/or promotion by insulin.The project consortium involves some of the most experienced pharmacoepidemiology groups in Europe, and a leading cancer research institute. The consortium will liaise closely with the European Medicines Agency and other stakeholders throughout the study."