Selecting targets for cancer prevention: where do we go from here?

Given the lack of progress in curing metastatic epithelial cancers, there is intense interest in, and a sound scientific rationale for, pursuing strategies to prevent cancer. However, although several clinical trials have shown efficacy in cancer prevention, few have resulted in changes to medical practice, and some trials have even shown harm. Recent experiences with serious side effects identified in cancer prevention trials underscore the need to re-evaluate our approach to clinical chemopreventive drug development, and to establish a framework for agent selection for future trials.