There has been quite a buzz lately surrounding the diabetic drug metformin, also known as Glucophage, as a potential anti-cancer agent. Metformin has been around for many years to treat Type II diabetes. In 2005, researchers unexpectedly discovered that diabetics taking metformin coincidentally had lower rates of cancer. Some reported as much as a 50 percent reduction in risk.
So how is it that this drug actually works to potentially reduce cancer risk? In short, metformin reduces the cellular mutation rate and the accumulation of DNA damage-mutations that are directly involved in carcinogenesis. Apparently, metformin reduces the levels of reactive oxygen species (ROS), i.e., oxidative species. ROSs are known to be DNA-damaging agents produced as by-products when cells generate energy from nutrients. This process takes place within the mitochondria which we all know is the “energy powerhouse” of the cell.
Metformin may also have an indirect effect on cancer cells via an insulin-mediated mechanism. This process suppresses gluconeogenesis in the liver, which in turn lowers circulating insulin levels throughout the body. The lower levels lead to decreased binding of insulin to insulin and insulin-like growth factor-1 receptors which are present on many cancer cells. The direct and indirect dual action effect on these cancer cells is showing promise for certain cancers already.
There are now reports that show a reduced risk of several common cancers including breast, lung, liver, pancreatic, prostate, and colorectal for patients with diabetes who are taking metformin. Interestingly, there is also discussion that metformin may decrease the cancer risk associated with insulin use. From an epidemiological standpoint, we have to consider lifestyle as well, such as obesity, smoking, history of any prior cancers, etc., before concluding that this diabetic agent is responsible for such a decrease in cancer risk. We also have to consider risks associated with using this particular drug such as renal function, hypoglycemia, and blood glucose monitoring.
Based on the evidence mentioned above, a growing number of intervention studies have been initiated, one including a Phase III breast cancer trial of metformin vs. placebo in early stage breast cancer: Metformin to Treat Early-Stage Breast Cancer.
As researchers and healthcare providers focus on cancer prevention, metformin may not only offer hope for our existing diabetic patients, but also for patients with cancer -- with or without diabetes.
For more information on metformin research, please visit: Metformin, Cancer Risk, and Prognosis.
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