Common diabetes drug could fight ovarian cancer

The commonly prescribed diabetes drug metformin could potentially double as an effective form of ovarian cancer treatment, according to a new study.

Researchers from the Mayo Clinic found that ovarian cancer patients – who also had diabetes – lived longer than other ovarian cancer patients when they were taking metformin.  According to the scientists, they had been researching the link between metformin and its potential anti-cancer properties for many years.

“We had a pretty good idea that metformin has anti-cancer activity, because a lot of people around the world have been reporting the link between metformin intake and a protective effect against cancer for a number of years now,” Dr. Sanjeev Kumar, a Mayo Clinic gynecologic oncology fellow, told  “[Viji Shridhar, one of the study’s co-authors,] has been conducting a lot of experiments in her lab and has published extensively in the area, so we had a lot of cell data, mice data – and then we decided to test our hypothesis in humans.”

Kumar and his colleagues examined 239 ovarian cancer patients, 61 of whom were taking metformin.  Compared with the other 178 patients, those taking metformin had a much higher survival rate – with 67 percent of the metformin-taking patients surviving after five years, versus 47 percent of those who were not taking the medication.

When taking into consideration other factors – such as the patients’ body mass indexes or the severity of their cancer – those who were taking metformin were four times more likely to survive than those who did not take the medication.

As for why the diabetes drug is so protective against cancer, the researchers cannot say for sure – but there are a few theories.

“That’s something that is actively under investigation right now, but people think that it may have a few areas on which [the drug] is active,” Kumar said.  “It has been shown to inhibit the region of cancer cells, and it also seems to inhibit the energy supply to the cell.  And it also may be acting on the cancer stem cells – cancer stem cells are thought to be engines of cancer growth.”

While the results of the study are promising, Kumar and Shridhar caution that the drug would not be a cure for ovarian cancer.  Instead, it could potentially be used in combination with already existing ovarian cancer treatments – to provide patients with the best overall therapy.

“It 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,” Kumar 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.”

Ovarian cancer is currently the fifth most common cancer among women and is the most deadly form of female reproductive cancer, according to the National Institutes of Health.  Patients are rarely diagnosed with ovarian cancer during its early stages, and the cancer has usually progressed extensively by the time it is caught.

The possibility of metformin being used as an approved ovarian cancer treatment is a ways off; however, Kumar said he hopes this study will spur further investigation into the link between the diabetes medication and anti-cancer effects.

“What we hope in the future is that large-scale, randomized clinical trials are conducted in ovarian cancer,” Kumar said. “Those have already been going on in breast cancer, and so we think ovarian cancer should follow suit.  If those clinical trials are positive, then I think metformin can be added to the other array of medications that we have for ovarian cancer – such as a platinum compounds and taxoid compounds.  We doubt it’s going to be the sole treatment.”

To better boost research into ovarian cancer, Kumar said a central message they have for patients is to get involved.

“More patients should inquire about clinical trials and more patients should enroll in clinical trials so we can have some of these answers earlier rather than later,” Kumar said.

The study was published online in the journal Cancer.