Scientists have discovered that a common type of oral bacteria can cause certain cancers to “melt away”.
Researchers at Guy’s and St Thomas’ and King’s College London said they were “brutally surprised” to find that fusobacterium – a type of bacteria commonly found in the mouth – has the ability to kill certain cancers.
People with head and neck cancer who were found to have this bacteria in their cancer were found to have much better outcomes, according to a study.
Researchers are now looking at the exact biological mechanisms behind the link to the initial findings.
Dr Miguel Reis Ferreira, the study’s senior author and a consultant in head and neck cancer at Guy’s and St Thomas’, told the PA news agency: “Essentially, we found that when you put these bacteria in head and neck cancer find, they have much better outcomes. The other thing we found is that this bacterium in cell cultures is able to kill cancer.
“What we’re finding is that this little bug causes a better outcome based on something it does in the cancer. So we’re currently looking for that mechanism, and that should be the theme for a new paper in the very near future .
He added: “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. However, this finding must be balanced by their known role in causing cancers such as making those in the gut worse.”
Scientists used modeling to help identify which bacteria might be of interest to investigate further. They then studied the effect of the bacteria on cancer cells in a laboratory and also conducted an analysis of data on 155 patients with head and neck cancer whose tumor information was provided to the Cancer Genome Atlas database.
Academics initially expected a different outcome as previous research linked fusobacterium to the progression of bowel cancer.
In the laboratory studies, researchers put amounts of the bacteria in petri dishes and left them for several days. When they returned to examine the effect of the bacteria on the cancer, they found that the cancer had almost disappeared.
They found there was a 70%-99% reduction in the number of viable cancer cells in head and neck cancer cells after they were infected with fusobacterium.
Analysis of the patient data found that those with fusobacterium in their cancer had a better chance of survival compared to those who did not. Fusobacterium detectability in head and neck cancers was associated with a 65% reduction in risk of death compared to patients whose cancers did not contain the bacteria.
Researchers hope the finding can help guide treatment for patients with head and neck cancer, which includes cancer of the mouth, throat, voice box, nose and sinuses.
Experts said there had been little therapeutic progress in head and neck cancer in the past 20 years, so it was hoped the finding could lead to new treatments in the future.
Reis Ferreira said that before the laboratory work, the team expected that fusobacterium would encourage these cancers to grow or make them more resistant to radiotherapy. But they actually found that “at the end of a few days it just completely destroys the cancer”.
“You put it in the cancer at very low amounts and it just starts killing it very quickly,” he said.
Dr Anjali Chander, a senior clinical research fellow at King’s College London and the lead author, said: “Our findings are remarkable and very surprising. We had a eureka moment when we found that our international colleagues had also found data which confirmed the discovery.”
Barbara Kasumu, the executive director of Guy’s Cancer Charity, which helped fund the study, said: “We are proud to support the ground-breaking research carried out by Miguel and Anjali, which aims to advance our understanding of head – and improving neck cancer and more compassionate effective treatments.”
