Cancer Chemoprevention: What Have we Learned?

Cancer is a major disease worldwide and different approaches are needed to reduce its risk. Previous laboratory studies suggested that cancer can be prevented by many naturally occurring and synthetic chemicals. In human cancer prevention studies, however, most of the successful examples are the repurposing of existing drugs, such as tamoxifen and aspirin. Epidemiological studies have established associations between certain dietary patterns or nutrient insufficiencies with elevated cancer risk. Laboratory research has also shown impressive results on the cancer preventive activities of constituents from food and beverages. However, such cancer preventive activities have not been demonstrated in many human intervention trials. This article reviews the advances in this field and discusses the reasons for the discrepancies between laboratory studies and human trials. Lessons learned for cancer prevention research in the past decades will be illustrated using studies with β-carotene, vitamin E, green tea polyphenols, tamoxifen, and aspirin as examples. In future studies, more interdisciplinary collaboration in the integration of laboratory and human studies are needed to advance the field of cancer chemoprevention. © 2017, Springer International Publishing AG.