Metformin and Cancer

Many people know metformin as a common oral medication for treating type 2 diabetes. What is less widely known is that metformin has also been shown to have anti-cancer effects.

What is metformin?

Metformin is a widely used oral medication for type 2 diabetes. Alongside its established role in managing blood glucose, it has attracted research interest for its potential effects on cancer.

How metformin may act on cancer

Metformin appears to affect cancer both directly and indirectly.

Directly, metformin interferes with cancer-promoting signalling pathways. In doing so, it inhibits the growth and proliferation of cancer cells, ultimately leading to their death.

Indirectly, metformin works by lowering blood glucose and insulin levels. Cancer cells feed on glucose and require higher glucose consumption than normal cells, so by reducing this so-called "food source," metformin is thought to inhibit their growth and reproduction.

Metformin can also be used synergistically with chemotherapy regimens to increase treatment efficacy.

What the studies show

Many studies have pointed to metformin's strong potential for cancer prevention and treatment. One study explains both the direct and indirect mechanisms of metformin on cancer cells, as well as its anti-ageing potential. Another has associated metformin with a decreased risk of breast, colon, liver, pancreas, prostate, endometrium and lung cancer. A study by Zhang and Guo examined the use of metformin in combination with chemotherapy regimens, and a further study suggested that metformin may be most effective against colorectal cancer and prostate cancer.

What this means for patients

These findings come from research into metformin's potential rather than from established cancer care. Metformin is not a standard cancer treatment, and the studies describe possible effects that are still being investigated.