Researchers were 'surprised' that patients with head and neck cancer who had Fusobacterium within their tumours had 'much better outcomes'.

The exact biological mechanisms behind the link are being further investigated by specialists. 

In laboratory studies, the team at Guy's and St Thomas', King's College London, put quantities of the bacteria in Petri dishes with cancer cells and left them for a couple of days.

They found there was a 70 to 99 per cent reduction in the number of viable head and neck cancer cells after being infected with Fusobacterium. 

Further analysis of 155 patients with head and neck cancer showed those with the bacteria within their tumours had better survival odds compared to those who did not, with a 65 per cent reduction in risk of death.

Researchers hope the findings could help guide treatment for patients with head and neck cancer – which include cancers of the mouth, throat, voice box, nose and sinuses. 

Experts said there have been few therapeutic advances in this field in the past 20 years, and it is hoped the finding could potentially lead to new treatments in the future.

'In essence, we found that when you find these bacteria within head and neck cancers, they have much better outcomes,' said senior author Dr Miguel Reis Ferreira. 

'The other thing we found is that, in cell cultures, this bacterium is capable of killing cancer.

'This research reveals that these bacteria play a more complex role than previously known in their relationship with cancer – that they essentially melt head and neck cancer cells. 

'What it could mean is that we can use these bacteria to better predict which patients are more likely to have good or worse outcomes.'