Ideally, practice guidelines for cancer prevention should reflect the available empirical evidence. Although the most persuasive arguments for the efficacy of an intervention come from randomized controlled trials (RCTs), such studies are not always feasible because of ethical or logistical reasons. The advent of evidence-based medicine has underscored the need for consortia of researchers specialized in reviewing the biomedical literature on a systematic basis, ranking studies according to their design, quality, and generalizability of results. This review summarizes the recommendations and policies on screening and prevention of specific types of cancers from North American and international organizations such as: the National Cancer Institute's Physicians's Data Query Program, the US Preventive Services Task Force, the Canadian Task Force on the Preventive Health Care Force, and the Cochrane Collaboration.