Repurposing old drugs to chemoprevention: the case of metformin

Area of Science:

• Oncology
• Pharmacology
• Epidemiology

Background:

• Epidemiologic studies suggest metformin use is associated with reduced cancer incidence and mortality.
• This association has not been consistently replicated in animal models or recent epidemiological research.

Purpose of the Study:

• To evaluate the chemopreventive potential of metformin.
• To review mechanisms of action, preclinical data, updated epidemiologic evidence, and clinical trial outcomes for metformin in cancer prevention.

Main Methods:

• Review of existing literature on metformin's mechanisms of action.
• Analysis of preclinical studies investigating metformin's efficacy.
• Examination of updated epidemiological data, accounting for biases and confounders.
• Assessment of recently completed and ongoing clinical trials involving metformin for cancer prevention.

Main Results:

• Inconsistent findings exist regarding metformin's effect on cancer incidence and mortality across different study types.
• Metformin's proposed mechanisms of action and preclinical data suggest potential anticancer properties.
• Updated epidemiological evidence and ongoing clinical trials are crucial for definitive conclusions.

Conclusions:

• Repurposing metformin for cancer prevention is appealing due to its established safety profile and known mechanisms.
• High-quality, late-phase clinical trials are essential to establish metformin's efficacy and determine optimal patient populations for cancer prevention.