Metformin and increased cancer survival

Metformin and increased cancer survival

Metformin seems to have several actions against cancer; it reduces blood glucose, inhibits insulin and IGF-1 production, reduces cholesterol and has an indirect effect on reducing m-TOR levels; a specific study on breast cancer suggests increased survival times.

Metformin, or Glucophage, is an anti-hyperglycemic drug which lowers blood glucose levels because it reduces glucose production in the liver and also improves uptake of blood glucose by cells;  however it does not increase insulin production.

It is used by the doctors and oncologists at Care Oncology as one of four drugs in the Care Oncology Protocol, as they claim: “These medicines target cholesterol, glucose and the glycolysis process, which impact on the metabolism of cancer cells and the immune cells around them”

In many of the early studies, patients were taking metformin because they had Type-2 diabetes. One study of women having breast cancer chemotherapy showed 24% of Type-2 diabetes patients taking metformin having complete remission, vs 16% non-diabetic patients vs 8% Type-2 diabetes patients not taking metformin. In HER2 positive cancer, patients taking metformin because of diabetes, had a 40% lower progression and death after 4.5 years than those not taking metformin.

According to MD Anderson, metformin affects multiple signaling processes to do with growth, proliferation and cell death. Dr Pamela Soliman was treating endometrial cancer patients with an m-Tor inhibitor everolimus and letrozole. m-Tor inhibition can reduce insulin secretion, so some patients were also prescribed metformin. The metforminaddition resulted in the patients responding far better to the drugs and a full clinical trial is now underway. Another trial is studying paclitaxel and carboplatin with and without metformin.

A colleague, Dr. Heath Skinner is conducting a trial using metformin or a placebo with people having radiotherapy for NSCLC.

A 2012 study by the Mayo Clinic involving women with ovarian cancer followed 61 patients with diabetes and 178 patients without. Comparing two matched samples, 67% of women taking metformin survived 5 years, compared to 47% of those not taking the drug.  Dr William Cliby, Director of the Department of Gynecology said, "Whichever way you looked at the figures, the women on metformin always did better."

In 2016, researchers from the Perelman School of Medicine, Pennsylvania showed that breast cancer patients who started taking metformin after their diagnosis were almost 50% more likely to survive than non-users. Lead Author Yun Rose said that they also looked at people who were already on metformin at the time of diagnosis and those people tended to be poor survivors possibly because they had chronic illness prior to diagnosis.

In a 2019 meta-study on prostate cancer (8), researchers concluded that there were clear survival benefits due to the multple action of metformin - "Evidence has shown that metformin has multiple anti-neoplastic effects through AMPK-dependent and independent mechanisms, an alteration of IGF-1 signaling, suppression of androgen receptor pathway, inhibition of mTor pathway, and liogenesis". 

After concerns were expressed that metformin given to Type-2 Diabetes patients could increase kidney cancer risk, a Taiwanese study of 2000 people followed up a decade later showed that users had a lowered incidence of Kidney cancer.

Some Metformin studies show no anti-cancer benefit 

       * A 2015 randomised controlled trial (11) of metformin with advanced pancreatic cancer, showed no impact on survival. 

       * A 2017 study (9) on the use of platinum based drugs with Lung cancer (NSCLC) showed no survival benefit in adding metformin.

Seven ways Metformin might help fight cancer

The use of metformin as a cancer preventative aid is highly controversial but rumour has it that it is popular amongst executives in Silicon Valley as a longevity aid as well as for cancer prevention. But the big interest amongst cancer experts is in using this diabetes drug as an anti-cancer drug. It's use is termed "Off-label" and metformin may be refered to as a 'repurposed' drug. Here we look at its possible benefits:

  1. Metformin has proven action in lowering blood sugar. It does this by reducing the ability of the liver to release glucose(1). Metformin actually accumulates in the liver. There can only be a few remaining quacks who deny that cancer cells not only mop up all available sugar, but they even rob healthy cells of theirs and change the insulin production system in the body to keep blood sugar available for their avarice - there was a study from Colorado Cancer Center on exactly this for leukaemia. There is now too much research on sugar promoting cancer to argue against.

Go to: 20 research links between sugar and cancer

  1. Metformin also lowers circulating levels of insulin(2), which has proven links to inflammation in the body via the COX-2 pathway. And inflammation aids metastases.
  2. Metformin lowers circulating levels of Insulin-like Growth Factor 1. Or IGF1, which plays a part in cancer development
  3. Metformin indirectly inhibits m-TOR. Eating a big meal leads to increased plasma levels of insulin and IGF-1. In turn these stimulate phosphoinositide 3-kinase (PI3K) and Akt and protein kinase B (PKB), which stimulate m-TOR, an important signaling pathway in cancer such as melanoma (4). Indeed, inhibiting m-TOR may be the crucial factor as it appears to play a pivitol role in the metabolism, growth and proliferation of cancer cells.
  4. Metformin also reduces fatty liver and lowers blood cholesterol levels(3). Heightened levels of blood cholesterol are linked to greater metastases in cancer patients.
  5. In an Oxford University review(7) of research on Metformin with prostate cancer, metformin appeared to help Androgen Deprivation Therapy work better. This may be due to its cholesterol-lowering abilities rather than its sugar-lowering ones.
  6. Research suggests Metformin seems to possess anti-tumour activity and promote cytoxic T-lymphocyte levels and can block the same PD-L1 as some new immunotherapy drugs target. These seems to occur via the AMPK pathway. Researchers are suggesting metformin should be used with PD-L1 immunotherapy drugs.

Go to: Fat and cancer spread

Chris Woollams, former Oxford University Biochemist and a founder of CANCERactive added, "Many of the specific studies on metformin have been with patients who have type-2 diabetes, and concern the reduced risk of cancer. For example, a 2018 study that Type-2 diabetes patients who took metformin had a lower risk of colorectal cancer (5). A previous study had shown a decreased risk of 54% in those taking metformin vs those not taking. Metformin is known to inhibit certain cancer cell lines. For example, metformin has been shown to inhibit brain cancer GBM cell lines in vitro, and also to have action in vivo(6). Clearly research is in its infancy. We need to know more".

Metformin warnings

1). New research shows that while metformin can inhibit most cancer cells by inhibiting TORC1, in the case of BRAF-mutant melanoma, melatonin accelerates their growth in vivo. However, VEGF inhibitors work in synergy with metformin against BRAF mutations.

BRAF mutations are found in approximately 70% of melanoma cancers. It would be wiser not to use metformin unless your oncologist agrees.

2). And here is a possible glitch. Metformin appears to contain N-Nitrosodimethylamine, or NDMA. This is the chemical that caused the recall of drugs such as Zantac. The FDA has stated that levels above 96 nannograms a day could be unsafe. The FDA even asked manufacturers to recall the drug.  

Go to: Concerns on Metformin

Dose of metformin in cancer

Professional expertise must be sought. Metformin usually comes in 500 mg pills and patients take 2-4 per day.

Is Berberine a natural alternative?

Side by side research has shown that the herbal ingredient Berberine is just as regulatory of blood glucose levels as metformin in type-2 diabetes. Berberine has also been shown in several studies to attack the cancer cell's energy production pathway, and to inhibit m-TOR (10); and berberine is also anti-microbial and anti-inflammatory.

The fact is that berberine and metformin, although they both lower blood sugar, have quite different benefits. People like Jane McLelland (who wrote the book 'How to starve cancer') and I prefer Berberine. There is even research that metformin and berberine can be used together and complement each other against cancer.

Go to: a review on Berberine as a cancer treatment 



  1. J Clin Endocrinol Metab. 2003 Mar;88(3):1323-32.
  2. Nat Med. 2000 Sep;6(9):998-1003.
  11. Lancet Oncol 2015, 16:839–847
2019 Research
CancerAcitve Logo
Subscribe (Free e-Newsletter)

Join Chris'

Market Place
Join Chris' NewsletterSignup today for free and be the first to get notified on new updates.