An NHS diabetes drug costing as little as 2p a tablet could cut prostate cancer risk by more than a third, a study suggests.
Metformin is already taken by millions to control blood sugar levels in type 2 diabetes. One of the biggest studies of its anti-cancer effects has found it could also work against a disease that kills more than 12,000 men a year in the UK.
Researchers said men most at risk of prostate cancer could in future be given metformin to help protect against it, though more work is needed.
Sophie Brooks, of Cancer Research UK, said: “More research is needed to understand how metformin might influence prostate cancer risk but these early signs are good news.”
The study was carried out by a team at the University of Sydney. They tracked almost 95,000 men from 2012 to 2019, identifying how many were diagnosed with prostate cancer and matching this against prescriptions for metformin.
Just over 5,000 of the men developed prostate tumours, but those taking the drug were 35 per cent less likely to receive a cancer diagnosis.
Many of the men studied were overweight or obese, both major risk factors for cancer. But the risk also fell in slim men taking metformin.
More than 60,000 men a year in the UK are diagnosed with prostate cancer, with cases rising by more than 40 per cent in the past 15 years.
Metformin has been studied as a potential treatment because research suggests it can block the reproduction of cancer cells. The drug lowers levels of insulin, a hormone which can help malignant, or cancerous, cells multiply.
Research has also found it may help treat breast cancer and prevent certain types of leukaemia.
Previous studies on metformin’s impact on prostate tumours focused on men who were already very ill, with limited success. The Sydney team said their evidence suggests the drug could be much more effective when given earlier, possibly before cancer has even been detected.
Simon Grieveson, of Prostate Cancer UK, said the charity is ‘supporting research into whether it can extend the lives for some patients, which would be a game-changer for many men’.
