Common bacteria in the mouth can ‘melt up to 99% of cancer cells’ and could lead to new treatments

A TYPE of bacteria that causes dental plaque can make certain cancers “melt” and almost completely disappear, scientists have discovered.

Scientists were “brutally surprised” to find that Fusobacterium appears to have the ability to kill up to 99 per cent of certain cancers.

People whose head and neck cancers had this bacteria within their tumours have also been found to have “much better outcomes”, according to a new study.

In the mouth, it’s one of the most common types of disease-causing bacteria, linked to gum disease and plaque buildup.

The science behind the new link is being looked into by researchers at Guy’s and St Thomas’ and King’s College London, after they made the discovery.

Their new study, conducted in collaboration with an international team of researchers, used several different methods to study the link.

Experts used modelling to help identify which bacteria may be of interest to further investigate.

Then they studied the effect of the bacteria on cancerous cells in a laboratory.

They also performed an analysis of tumour data of 155 patients with head and neck cancer.

In the laboratory studies, researchers put quantities of the bacteria in Petri dishes and left them for a couple of days.

When they returned to inspect the effect of the bacteria on the cancer, they found that the cancer almost disappeared.

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

An analysis of the patient data found that those with Fusobacterium bacteria within their cancer had better survival odds compared with those who did not.

Fusobacterium in head and neck cancers was associated with a 65 per cent reduction in risk of death compared with patients whose cancers did not contain the bacteria.

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

Academics initially expected a completely different outcome as previous research has linked Fusobacterium to the progression of bowel cancer.

NEW TREATMENTS

There have been very few therapeutic advances in head and neck cancer in the last 20 years so it is hoped the finding could potentially lead to new treatments in the future.

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

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

“What we’re finding is that this little bug is causing a better outcome based on something that it’s doing inside the cancer.

“So we are looking for that mechanism at present, and it should be the theme for a new paper in the very short-term future.”

Dr Reis Ferreira, a consultant in head and neck cancers at Guy’s and St Thomas’ at King’s College London, added: “This research reveals that these bacteria play a more complex role than previously known in their relationship with cancer.

“[We now know] they essentially melt head and neck cancer cells. However, this finding should be balanced by their known role in making cancers, such as those in the bowel, get worse.

“The research in colorectal cancer indicates that these bacteria are bad, and that was kind of ingrained into our minds, and we were expecting to find the same thing.

“When we started finding things the other way around, we were brutally surprised.”

‘GROUNDBREAKING’

Dr Reis Ferreira said that before the lab work, led by Dr Anjali Chander, the team expected for Fusobacterium to encourage these cancers to grow or make them more resistant to radiotherapy.

But they actually found “at the end of a few days, it just destroys the cancer completely”, they said.

“You put it in the cancer at very low quantities and it just starts killing it very quickly,” he said.

“And then we got the validation cohort in collaboration with an Italian group from Milan via (researcher) Tiziana Rancati.”

Dr Anjali Chander, senior clinical research fellow at King’s College London and lead author, added: “Our findings are remarkable and very surprising.

“We had a eureka moment when we found that our international colleagues also found data that validated the discovery.”

Dr Reis Ferreira added: “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.

“And based on that, we could change their treatment so make it kinder in the patients that have better outcomes, or make it more intense in patients that are more likely to have their cancers come back.”

Scientists have published a paper on the finding in the journal Cancer Communications, which describes how Fusobacterium is “toxic” for head and neck cancer and how its presence “may determine a better prognosis”.

“Fusobacterium detectability was associated with both better overall survival and better disease-specific survival,” the authors wrote.

Barbara Kasumu, executive director of Guy’s Cancer Charity, which helped fund the study, said: “We are proud to support the ground-breaking research conducted by Miguel and Anjali, which aims to enhance our understanding of head and neck cancer and develop more compassionate and effective treatments.”