Metformin and increased cancer survival

Metformin and increased cancer survival

Metformin may have several actions against cancer as 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 glucose production in the liver and improves uptake of glucose by cells but does not increase insulin production.

In many of the early studies, patients were taking metformin because they had 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 resulted in 40% lower progression and death after 4.5 years than those not taking metformin.

According to MD Anderson, metformin affects multiple signalling 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 metformin meant that the patients responded far better to the drugs and a full clinical trial is underway. Another trial is studying paclitaxel and carboplatin with and without metformin.

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

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.

Six ways Metformin may help fight cancer

The use of metformin as a cancer preventative aid is highly controversial. But increasingly, some cancer oncologists are turning to metformin as an anti-cancer 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 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).
  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 appears to help Androgen Deprivation Therapy work better. This may be due to its cholesterol lowering abilities that 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 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 concerns

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.

Dose of metformin in cancer

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


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. 

Go to: Concerns on Metformin

Is Berberine a natural alternative?

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