Explain Cancer and Inhibition of Tumorigenesis?

Polyphenols appear to play a preventive role although the molecular mechanisms of action and applicability to human cancer prevention are unclear. Various studies appear to suggest that they may be effective when given in the post initiation period i.e. they are more helpful in inhibiting tumor promotion and progression. Most studies have been conducted either in vitro or in vivo in animals. Hence, we must be cautious in extrapolating these observations to humans.