Home > Alternative Therapies, Women's Health > Metformin and Cancer

Metformin and Cancer

August 3, 2009 Written by JP    [Font too small?]

There’s an extract of French lilac (Galega officinalis) that’s been attracting a lot of attention lately in the field of oncology. Perhaps the news of yet another “natural” cancer fighting compound is no longer a surprise to readers of this site. But would it surprise you to discover that the particular substance I’m referring to is actually a prescription medication that’s generally used to help manage diabetes? The drug in question is metformin. It’s a medication that was developed over 50 years ago and is often used to combat non-alcoholic fatty liver disease (NAFLD) and polycystic ovary syndrome (PCOS). It also supports cardiovascular health and promotes weight loss/maintenance in those with blood sugar abnormalities and metabolic disorders. It’s estimated that over 35,000,000 prescriptions for metformin were written in 2008 alone. This figure is likely to increase in the future for a few very important reasons. It’s cheaper and more effective than many of the newer medications in its class, and this is one drug that may actually help save lives.

Pancreatic cancer is number four on this list of most deadly cancers. This year alone, over 35,000 Americans will lose their battle with this malignancy. Diabetics have an increased risk of contracting this form of cancer, but new data from the prestigious M.D. Anderson Cancer Center is pointing to a potential preventive effect afforded by an old reliable drug.

A 4 year population study of over 1,800 participants (973 with pancreatic adenocarcinoma and 863 without) found that diabetics who were using metformin exhibited a 62% reduced risk of pancreatic cancer. Two significant factors were noted: 1) Those also using insulin and other anti-diabetic medications (without metformin) actually had a dramatic increase in pancreatic cancer risk (2.5 – 5 times the risk); 2) Exercising, controlling blood sugar, dieting and quitting smoking did not seem to improve the benefits of metformin. (1)

This isn’t the first time that metformin has been associated with a reduced incidence of tumors. A study published in the July edition of the journal Diabetologia found that the use of insulin and sulfonylureas (another variety of anti-diabetic medications) resulted in an increased risk of solid tumors (colorectal and pancreatic). On the other hand, adding metformin to either of these treatments “reduced progression to cancer”. A similar pattern appears to be present when looking at 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 the course 9 years, approximately 7% of those using metformin developed cancer. Over 11% of those not using 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% reduced risk that was attributed to metformin use alone. This is a very important observation because the role that diabetes treatment plays in cancer development/treatment is in desperate need of clarification. (4,5)

In recent months, several studies have emerged indicating that metformin may play a part as an adjunct to other conventional cancer therapies. One trial determined that women receiving metformin along with chemotherapy showed a greater rate of “pathologic complete response” to said therapies. In fact, the women involved responded three times as well when provided with the added metformin. Perhaps this is why there’s been an industry-wide call to thoroughly evaluate the potential of this anti-diabetic medication in further breast cancer trials. Several clinical studies are already in the works to address this and much broader issues relating to cancer in general. There’s even evidence that metformin may improve the efficacy of the much touted cancer vaccines that are currently undergoing clinical evaluation. The mechanism behind the metformin/vaccine combo is thought to be selective immune stimulation. (6,7,8,9,10,11)

Breast Cancer Response Rates

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

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

A real concern about long term metformin use is its impact on vitamin B12 concentrations. Earlier this year, a presentation at the American Diabetes Association’s 69th Annual Scientific Sessions reported that as many as 40% of metformin users exhibited some degree of vitamin B12 deficiency. Perhaps even more importantly, 77% of metformin patients had been diagnosed with a form of painful nerve damage known as peripheral neuropathy, which may partially be a consequence of a lack of this vital nutrient. Therefore, anyone who is using this medication ought to be regularly screened to rule out insufficient levels of B12. The good news is that supplementing with B-vitamins is easy, inexpensive and safe. Emerging evidence also suggests that maintaining adequate B-viamin status (particularly vitamin B6, B12 and folic acid) may result in even greater cardiovascular protection for metformin users. (16,17)

The decision as to whether to use any medication needs to be carefully evaluated by both doctor and patient. Even a relatively benign drug, like metformin, can cause digestive issues and rare, but severe, complications such as lactic acidosis (excessive acidity in the body). The key is to balance the expected gains with the possible risks involved. (18,19) I hope today’s column will inspire a more receptive attitude to the option of using certain medications where they’re indicated. Choosing selectively from both the allopathic and holistic camps, will truly give us the best of both worlds.

Be well!


Tags: , ,
Posted in Alternative Therapies, Women's Health

25 Comments & Updates to “Metformin and Cancer”

  1. Iggy Dalrymple Says:

    You metformin has got to be good if the FDA kept it from Americans for 40 years.

  2. JP Says:

    The FDA was pretty late to the game in terms of metformin approval. That’s for sure. 🙂

    Be well!


  3. Sai Says:


    I was told that Vitamin B12 was best implemented in the form of a injection once in 6 months. If you happen to know a good B12 supplement in particular please share with us. Thanks again for a very good post.

    Best Regards


  4. libby niles Says:

    Real B12 is
    Methylcobalamin the other is synthetic

  5. JP Says:


    It’s true that many doctors and nutritionists still prefer administering B12 by injection. But, it doesn’t appear that this is necessary in many circumstances.

    At the moment, I’m getting B12 (from my multi-vitamin/minerals) in two forms: cyanocobalamin (the most common form) and methylcobalamin (one of the “active/coenzyme” forms). I think the latter is often preferable – please review the second link.



    It’s important that adequate (oral) dosages are used (covered in the first link) and to have periodic blood tests to ensure that the oral B12 is working in an acceptable fashion.

    A third option that some people utilize is a sublingual (under the tongue) form of B12. The idea here is that an easy to dissolve mini-tablet is placed under the tongue and the B12 is absorbed via the tissue and capillaries found there. This is claimed to be a more direct way of getting B12 into the bloodstream. But again, this doesn’t appear to be an essential route of administration for most people either.



    Be well!


  6. Holly Says:

    Thanks for this information! I’ve been kicking myself for being on this drug for so long (due to pcos) and worried about being on any drugs at all was hoping to not have to take it soon…now I’m not going to worry about it and am glad I already take a nice Bcomplex on top of it!!

  7. JP Says:


    I’m happy to hear the information was helpful. 🙂

    You may be interested to know (if you don’t already know) that cinnamon may help PCOS as well.


    Be well!


  8. Bob Bailey Says:

    Fighting Cancer
    While there is no single drug, herb or treatment that will kill cancer, there are some things that can be done to build up the body’s immune system in order to prevent cancer in the first place. This includes:
    1. Eliminate sugar and junk food. Too much white sugar prevents white blood cells from fighting off infections. Just 25 teaspoonfuls of sugar will paralyze 92% of the white blood cells for five hours. The average American consumes 42 teaspoonfuls per day.
    2. Eliminate high fat. Studies have shown an increase in breast cancer in women who have a diet that is high in fat.
    3. Go on a raw food diet. This is difficult to do but it is also very important to do. Herein only raw fruits, vegetables, nuts and sprouted grains should be eaten while anything cooked should be avoided. The reason that this is so important is that raw food is still alive and possesses a very high nutrition level. It contains a lot of enzymes, minerals, phytochemicals and vitamins that are killed off by the cooking process. Cancer cells have been shown to die off on a raw food diet.
    4. Do not snack. Each eating episode during the day will increase a person’s risk of developing colon cancer. This is why it is important to stick to only eating three healthy meals a day with no snacks between them.
    5. Drink between one and three glasses of carrot juice daily. There is a lot of Vitamin A in carrot juice, which is important in fighting and preventing cancer. Vitamin A can also inhibit or retard tumors. Make sure to drink it 15 to 30 minutes before a meal.
    6. Drink plenty of water. To find out how much to drink, divide your weight in half. This is how many ounces of pure, soft water you need to drink every 24 hours. If you are working out or in the sun, you will need to drink more water.
    7. Sunbathe daily. Ten minutes of sun everyday without any sunscreen and with no sunglasses on is a good thing for the body as it will increase the production of white blood cells. It will help to fight off carcinoma, sarcoma and leukemia.
    8. Walk barefoot each day. The earth has an electrical frequency that is normal while cancer cells have a different frequency that is abnormal. It is easy for the human body to get off of the correct electrical frequency. To get it back on track it is important to stand or walk barefoot on the soil 10 minutes a day.
    9. Get plenty of fresh air. Breathing in good, clean, fresh air will help to cleanse your lungs and increase your circulation, killing off cancer cells which cannot live in the presence of oxygen. This is especially true of air that is near an ocean, river or waterfall or after a rain storm. It is also a good idea to sleep with a window open.
    10. Exercise outside. Walking up to five miles per day is a great way to get exercise and doing it outside is 10 times better than doing it inside because there is sun and fresh air there.
    11. Get sever or eight hours of sleep per night. Get to bed as early as possible because every hour of sleep before midnight is twice as beneficial as those that occur after midnight.
    12. Use of Herbs. Red clover flower, not the roots or stems, is a great herb for any type of cancer. It contains biotin, choline, copper, coumarins, glycosides, inositol, magnesium, manganesel, and selenium as well as vitamins: A, B1, B3, B5, B6, B9, B12, B17, C, P and the mineral Zinc. Don’t take the capsule but instead make a tea out of it twice a day on an empty stomach. This has been done for hundreds of years with great results.
    13. Learn how to deal with stress. The reason that this is important because cancer often occurs after a period of extreme stress. This shows that the mind greatly impacts the body.
    There are some simple things that can be done to improve upon the lives of cancer patients. It is even possible for a body to heal itself from cancer without the use of expensive, and sometimes dangerous, treatments.

  9. JP Says:

    Thanks for sharing those, Bob.

    I agree with many of your suggestions.

    Be well!


  10. Anonymous Says:

    Recently it has been found that diabetes drug metformin can also treat breast cancer. Those diabetics consuming metformin are less prone to getting cancer. It has the potential to destroy breast cancer stem cells. Metformin and chemotherapy had an amazing synergy with each other.

  11. JP Says:

    Thank you for sharing that. I’ll soon update this column to include that research and other breaking studies on this subject matter. It’s an exciting line of study to be sure!

    Be well!


  12. Gicel Says:

    Me parece muy interesante los beneficios que tiene la metformina, me gustaria saber si tienen alguna información sobre los resultados obtenidos con el cancer linfatico (Linfoma Hodking),y si es recomendado en pacientes de una edad abanzada y un cancer terminal. Gracias seria de gran ayuda contar con esta información.

  13. JP Says:


    Este estudio puede ser de interés:


    Estar bien!


  14. janet-lee ouimet Says:

    i recently read pages re the possible side effects of the type 2 diabetes drug metformin and the newest breakthrough, using this drug for cancer treatment:- Question-if one doesn’t have diabetes or any other health issue besides cancer, how might this drug affect them; i.e. their blood-sugar level?

  15. JP Says:


    Metformin does carry a few potential side effects. It is sometimes used for other conditions (besides diabetes) such as polycystic ovarian syndrome. Certain physicians also recommend it to protect against increasing insulin resistance that often accompanies aging. All of this information is summarized quite well in the article linked below.


    Blood pressure, blood sugar and lipid levels may be affected and should be monitored along with cardiac, kidney and liver function.

    Be well!


  16. janet-lee ouimet Says:

    would there be any benefit to taking the extract of the french lilact as a supplement in one’s fight against cancer, along with other boosting factors such as mushrooms and esiac and can one buy the french lilac at most health food stores, or where may one find it? Thanx, and another thank you for your great response to my last posting, including added info links- very informative and helpful! Jan

  17. JP Says:


    French lilac is sold as a dietary supplement commonly known as Goat’s Rue. Preliminary evidence suggests that it may possess similar blood sugar modulating activity as Metformin. However, I just don’t think there’s enough evidence to support its use in this respect.


    From a preventive standpoint, I try to keep a tight rein on my blood sugar levels via diet and lifestyle factors (exercise, stress management, etc.). It appears that preventing diabetes and related blood sugar abnormalities can reduce the risk of some cancers.


    Be well!


  18. Richard Feinman Says:

    By coincidence, I was at a big award-fund raising ceremony at the New York Academy of Sciences which had some scientific celebrities including Jim Watson who told me that he is about to publish a paper on cancer and metformin. I pointed out that metformin does the same thing as carbohydrate restriction and he agreed that sugar would be bad. I refrained from phrasing it as “it has not escaped my attention that…” (the under-stated phrase in the original Watson-Crick DNA paper).

  19. JP Says:

    Dr. Feinman,

    It never ceases to amaze me (and you, I’m sure) that diet is generally the last thing researchers will recommend. Instead, they seem to prefer medications that mimic the effects of healthy diet or lifestyle choices.

    I’m glad there are still some researchers out there like you that haven’t adopted this point of view. Some of us still prefer to do things the old fashioned/traditional way! There’s more satisfaction when you actually participate in your own wellness – rather than just popping a pill, IMO.

    Be well!


  20. donna Says:

    my brother has liver cancer and is diabetic, 2 conflicting reports from 2 different liver doctors, 1 says the metformin he takes for the diabetes is actually good for the liver, and will improve the liver, the other swears it is no good, of course we are confused, does anyone really know

  21. JP Says:


    Unfortunately, I’m not in a position to resolve this tie-breaker. I can only share a few recent studies that may be of interest:




    I hope this helps in some small way. I wish you and your brother all the best.

    Be well!


  22. Sue Says:

    On Bobs list eliminate high fat foods and drink carrot juice for vitamin A. If you are eliminating sugar would need a diet with more protein and fat. Also animal foods give you vitamin A.

  23. Ray Says:

    I couldn’t believe when I first saw the ABC Nightly News piece on Metformin & cancer. I screamed so loud. My dad was put on Metformin years ago by our small town family practioner. He was & is not diabetic. In January, they found a 9-12 cm tumor on his liver. He has another smaller tumor also. This isn’t definitive proof that their studies are wrong but in my dad’s case it’s totally wrong.

    By the way, this same family doctor had him on high blood pressure meds and he was dizzy all the time. He also kept him on heart meds when his cardiologist said there was nothing wrong with his heart. Everytime my dad saw him he asked to be taken off all these pills & he’d always say no. I wound up taking him off them & he is no longer dizzy. He is, however, on hospice after chemo therapy ruined the quality of his life. He’s improving still the tumors will have their way sooner or later.

    My point is trust what you know your body is telling you. Don’t let someone who has MD on their name tell you what to do. Use their knowledge & yours to decide what is right for you.

  24. Mrs.Debra Goforth Says:

    my husband has taken metformin for over15 years now he has liver cancer and his time left wih us is unknown.
    I have read that 7% will infact get cancer for the use of his drug. use caution.
    i will be looking more in depth in my husbands matter.
    his regular doctor did blood work every three months it wasnt ubtil he fell really sick the hisiptal found the cancer now its so far along no help. we have hospice.
    so be aware of all the side effects wih this drug

  25. JP Says:

    Hello Mrs. Goforth,

    First and foremost, I’m very sorry about your husband’s diagnosis. And, I wish you both the very best under these difficult circumstances.

    Based on my understanding, liver cancer risk is much higher in diabetics than in the general population. So, one question worth considering is whether or not it’s the medication or some other component of diabetes that is a primary factor.



    Please know that I’m not trying to dissuade you from investigating any and all possible causes of your husband’s illness. I just wanted to contribute a few links that may help you on your quest for the truth.

    Kind regards,


Leave a Comment