Current state and future challenges of chemoprevention.

There have been numerous chemoprevention trials in the past 10 years, but the number of approved chemoprevention drugs is still quite small. This is likely due to a number of factors, but two consistent problems in the field of chemoprevention have been the lack of efficacy with or without unacceptable toxicity, and unexpected toxicity or fear of it associated with most of the approaches. This review intends to describe the types of chemoprevention as well as highlight recent successes and failures. We will also discuss potential solutions for the problems of limited efficacy and toxicity.