Targeting angiogenesis -- a novel mode in cancer chemoprevention.

Cancer prevention is fast emerging as a discipline with a promising potential. Chemoprevention has its rationale in the multistage process of carcinogenesis which provides an option for development of preventive approaches in the early, premalignant stages, before appearance of clinical symptoms. Evidence is mounting that the angiogenic switch may be an early event in carcinogenesis. Most chemopreventive agents currently under development probably act via multiple mechanisms. The chemopreventives used in clinical trials, such as nonsteroidal anti-inflammatories, tamoxifen and retinoids, have been shown to inhibit angiogenesis, the formation of new vessels from existing vasculature, which may contribute to their protective effect. Development and use, alone or in combination with other agents with other mechanisms of action, of specific antiangiogenic agents is likely to open new possibilities in cancer chemoprevention.