Metformin and Cancer

There is an extract from the French lilac (Galega officinalis) which has been attracting much attention lately in the field of oncology. Perhaps the news of yet another “natural” cancer fighting connection is no longer a surprise to readers of this site. But would it surprise you to discover that this particular matter I refer to is in fact a prescription medication that is commonly used to help manage diabetes? The relevant drug is metformin. It is a drug that was more than 50 years ago and is often used for non-alcoholic fatty liver disease (NAFLD) and polycystic ovary syndrome (PCOS) to fight. It also supports cardiovascular health and promotes weight loss / maintenance in those with blood sugar abnormalities and metabolic disorders. It is estimated that more than 35 million prescriptions for metformin were written in 2008 alone. This figure is likely to increase in the future for some very important reasons. It is cheaper and more effective than many of the newer drugs in its class, and this is a drug that can actually help save lives.


Pancreatic cancer is number four on the list of the most deadly forms of cancer. This year alone, more than 35,000 Americans lose their battle with this malignancy. Diabetics have an increased risk of this cancer, but new data from the prestigious MD Anderson Cancer Center points to a possible preventive effect offered by an old reliable drug.

A 4 year population study of more than 1800 participants (973 with pancreatic adenocarcinoma and 863 without) found that people with diabetes who were using metformin, a 62% reduced risk of pancreatic cancer exhibited. Two important factors have been identified: 1) That also using insulin and other anti-diabetic medication (without metformin) actually had a dramatic increase in the risk of pancreatic cancer (2.5 – 5 times the risk) – 2) Exercise, controlling blood sugar, diet and smoking cessation did not seem to explain the benefits of metformin. (1)

This is not the first time that metformin is associated with reduced incidence of tumors. A study published in the July issue of the journal Diabetologia found that the use of insulin and sulfonylureas (another variety of the anti-diabetic medication) resulted in an increased risk of solid tumors (colorectal and pancreas). On the other hand, addition of metformin, these treatments are “reduced progression of cancer.” A similar pattern appears to be present when watching diabetic patients with liver cancer (hepatocellular carcinoma). (2,3)

The June 2009 issue of Diabetes Care also reports on the rate of cancer in a group of 8,000 + type 2 diabetics. Over 9 years, about 7% of the users of metformin developed cancer. Over 11% of those who do not use this medication were diagnosed with malignancies. Even after taking into account various factors such as age, blood sugar control, smoking and weight, there was still an estimated 37% less chance that was attributed to metformin use. This is a very important observation, because the role that diabetes plays in the development of cancer / treatment is an urgent need for clarification. (4,5)

In recent months several studies have indicated indicates that metformin may play a role in addition to other conventional cancer therapies. One study found that women taking metformin, along with chemotherapy is a greater degree of “pathological complete response” to see mentioned therapies. In fact, the women who responded three times as good as those with the added metformin. Perhaps this is why there has been an industry-wide call for thorough evaluation of the capabilities of this anti-diabetic medication in the subsequent breast cancer trials. Several clinical studies are already in the works of these and many broader issues related to cancer in general to address. There is even evidence that metformin may reduce the effectiveness of the acclaimed cancer vaccines currently in clinical evaluation. The mechanism behind the metformin / combo vaccine is believed to be selective immune stimulation. (6,7,8,9,10,11)

Breast cancer response

Journal of Clinical Oncology, Vol 27, No 20, 2009 (link)

The above information is certainly reason for optimism. But as with all medications and supplements, it is important to be aware of known contraindications and interactions. For the most part, metformin has a pretty solid safety. In fact, in recent years it has constantly distinguished from similar drugs by actually supporting heart health (cancer in addition to its positive track record). A survey in June 2009 that a 24% reduced risk of congestive heart failure and a 46% lower overall mortality when metformin was compared with a sulphonylurea (another type 2 diabetes medication) recorded. (12,13,14,15)

A real concern about the long-term metformin use is its impact on vitamin B12 concentrations. Earlier this year, a presentation at the 69th Annual American Diabetes Association’s Scientific Sessions reported that a whopping 40% of metformin users a degree of vitamin B12 deficiency exhibited. Perhaps more importantly, 77% of metformin patients diagnosed with a form of painful nerve damage known as peripheral neuropathy, may be partly due to a lack of this essential nutrient. Therefore, anyone using this medication should be regularly screened to exclude insufficient level of B12. The good news is that supplementing with B vitamins is easy, cheap and safe. Emerging evidence also suggests that maintaining adequate B-viamin status (especially vitamin B6, B12 and folic acid) may lead to even greater cardiovascular protection for metformin users. (16,17)

The decision about whether to use all medications should be carefully reviewed by both doctor and patient. Even a relatively benign drug such as metformin, can lead to digestive problems and rare, but serious complications such as lactic acidosis (too much acid in the body). The key is to balance the expected benefits of the possible risks. (18,19) I hope that the current column is a more open attitude towards the possibility of using certain medications where they indicated inspire. Choosing selectively from both allopathic and holistic camps will really us the best of both worlds.

Be good!

Posted in Alternative Therapies, nutrition.