The safe, low-cost diabetes drug metformin is believed to have contributed to survival rates of women with ovarian cancer, according to a new study by the Mayo Clinic. Women taking metformin to treat diabetes lived longer than women at the same stage of cancer who did not have diabetes and did not take metformin.
The study, which was published online Monday in the journal Cancer, found that out of 239 women undergoing the same chemotherapy regimen, 67 percent of those taking metformin were alive five years after their diagnosis. Of the 178 women not taking metformin, 47 percent were alive five years later.
Once factors such as patients' body mass indexes and severity of cancer were accounted for, analysis showed that those taking metformin were four times more likely to survive than those who did not take the medication.
Metformin's Anti-Cancer Properties
For years, scientists have been examining metformin's anti-cancer properties. Viji Shridhar, one of the Mayo Clinic researchers, has published heavily in this area, after spending hours in the lab examining mice and cell data.
She said it's probable that "metformin results in starving the cancer cells of their energy source — namely glucose — inhibiting the growth of these cells."
Another ovarian cancer study produced similar results to the Mayo study, with 73 percent of the patients taking metformin alive after five years, and less than half of the patients not taking metformin alive after five years, according to MyHealthNewsDaily.com.
Around 22,000 U. S. women are diagnosed with ovarian cancer each year, and the National Cancer Institute estimates that more than 15,000 women will die of ovarian cancer in 2012.
Although a direct cause-effect link has not been proven, the association between metformin and higher cancer survival rates is fueling researchers to explore metformin further.
Metformin: Safe and Effective
Dr. Sanjeev Kumar, one of the Mayo researchers, spoke to FoxNews.com about why metformin is such a good drug to investigate.
"It [metformin] can be very beneficial, because the best part about metformin is that it has a very, very good safety profile, and it has been in use for a long, long time,” he said. “It’s one of the most commonly prescribed diabetes medications. We already have a lot of safety data for this medication, and it’s FDA approved."
Metformin, sold as Glucophage and Fortamet, has been around for decades and hit the U.S. market in 1995. It has been used by millions of Americans with type 2 diabetes. The drug is both inexpensive and the only anti-diabetic drug in this study that provided a survival advantage for ovarian cancer patients.
Risk from Other Diabetes Drugs
More and more doctors appear to be switching patients back to metformin, the first line of treatment, from Actos, another oral diabetes medication. Consumer Reports recommends metformin and advises patients to avoid Actos, which comes with the risk of several serious side effects.
Actos (pioglitazone) carries a black-box warning from the FDA that the drug increases the risk of congestive heart failure. Additionally, a long-term study found that patients taking Actos for more than 12 months have a 40 percent increased risk of bladder cancer.
With millions of people diagnosed with type 2 diabetes every year, anti-diabetes drugs continue to be developed and studied. More studies may show that metformin doubles as an anti-cancer drug, but it has not yet been approved to treat cancer.