Harmful bacteria and fungi living in your mouth could triple your risk of developing pancreatic cancer, a study has suggested.

Experts have long believed that people with poor oral hygiene are more vulnerable to a host of diseases—including cancer—than those with healthier mouths.

But now scientists from NYU School of Medicine, have discovered which bacteria could increase the risk, theorising that the harmful bugs originating in the mouth can be carried by saliva into the pancreas.

Writing in the journal JAMA Oncology, Dr Richard Hayes, expert in population health and study co-author, said: ‘It is clearer than ever that brushing and flossing your teeth may not only help prevent periodontal disease but may also protect against cancer.’

The oral microbiome—the community of bacteria and fungi that live in the mouth—is increasingly being studied for its potential role in disease.

In the current study, researchers found for the first time that a type of yeast called candida—which naturally lives on the skin and throughout the body—may play a role in pancreatic cancer.

In the largest study of its kind, researchers examined data from two ongoing investigations tracking 900 American participants to better understand how lifestyle factors, such as smoking, and medical history are involved in cancer development.

At the beginning of the study, participants—from the American Cancer Society Cancer Prevention Study II and the Prostate, Lung Colorectal and Ovarian Cancer Screening Trial—rinsed with mouthwash and provided saliva samples.

Researchers then followed the participants for around nine years to record any presence of cancerous tumours.

The researchers then compared the bacterial and fungal DNA from saliva samples of 445 pancreatic cancer patients to that of another 445 randomly selected cancer-free participants.

After accounting for confounding factors known to increase the risk of the disease, such as smoking, age and race, the researchers identified 24 species of bacteria and fungi that either increased or slashed pancreatic cancer risk.

Another three bacteria linked to the cancer were already known to cause a nasty gum infection that can eat away at the jawbone and soft tissue surrounding the teeth, known as periodontal disease.

Altogether, the entire group of harmful microbes increased the risk of developing the cancer by more than threefold.

By assessing the makeup of each participant’s oral microbiome, the researchers were able to develop a tool that could estimate individual cancer risk.

Professor Jiyoung Ahn, study co-author, said: ‘By profiling bacterial and fungal populations in the mouth, oncologists may be able to flag those most in need of pancreatic cancer screening.’

However, the researchers emphasised that at this point, their findings cannot confirm a direct cause-and-effect link, but rather a correlation between cancer risk and certain microbes in the mouth.

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They now plan to explore whether oral viruses—like oral thrush—could contribute to cancer and how the mouth’s microbiome could affect a patient’s’ prognosis.

Pancreatic cancer—dubbed a ‘silent killer’ due to its subtle symptoms—kills just over 10,000 patients every year, about one death every hour.

And by 2040, cases are expected to hit record highs with 201,000 cases of the deadly cancer expected to be diagnosed.

Pancreatic cancer is typically caught at late stages, as warring signs are easily mistaken for other problems.

When spotted early, before it has spread throughout the body, around half of patients will survive at least a year.

But if the cancer has already spread beyond the organ—as happens for the majority of patients—only one in 10 patients will survive.

While pancreatic cancer is most likely to strike people over the age 75—younger groups can also get the disease.

Last year the Daily Mail highlighted a ‘frightening‘ explosion of young women developing the disease.

Rates of pancreatic cancer have soared by up to 200 per cent in women under the age of 25 since the 1990s.

Whilst numbers remain low, oncologists cannot explain the surge in young women, with no such spike noted in men of the same age.

Overall, incidences of the disease have increased by around 17 per cent in Britain over the same timespan, with soaring obesity rates and environmental factors suspected to be behind the trend.

Potential symptoms of pancreatic cancer include jaundice, where the whites of the eyes and skin turn a yellow hue, alongside itchy skin and darker urine.

Other possible signs include loss of appetite, unintended weight loss, constipation or bloating.

While these symptoms are unlikely to be cancer it is important that they are checked out by a GP early just in case, especially if people have had them for over four weeks.