Types of mouth bacteria linked to pancreatic cancer

Particular types of mouth bacteria may be linked to the development of pancreatic cancer, research suggests.

Pancreatic cancer has the worst survival rate of the most cancers, as it is usually diagnosed in the later stages. Each year, more than 7,500 people in the UK are diagnosed with pancreatic cancer, and around 6,500 die of it.

But a small study, published in the journal Gut, found that certain types of bacteria, some of which are found in gum disease, appear to be associated with the development of the disease.
The findings raise the possibility of curbing the progress of one of the most difficult cancers to treat, by altering the balance of bacteria, said researchers from the University of California.
The researchers compared the bacteria in saliva samples taken from 10 patients with pancreatic cancer which had not yet spread and from 10 healthy volunteers, matched for sex and age.
The patient samples contained 31 additional types of bacteria, and 25 fewer other types compared with those from the healthy volunteers.
They then checked the saliva samples from a further 28 pancreatic cancer patients and 28 healthy people to verify their findings.
They also examined saliva samples from 28 patients with chronic inflammation of the pancreas (chronic pancreatitis), associated with an increased risk of developing pancreatic cancer.
The researchers discovered that two species of bacteria - Neisseria elongata (N elongata) and Streptococcus mitis (S mitis) - showed up significantly less often in the mouths of the cancer patients than in those of the healthy people.

But levels of another species of bacteria - Granulicatella adjacens (G adjacens) - were significantly higher in the patients' mouths.
The scientists said that the combination of N elongata and S mitis accurately differentiated between healthy patients and those with cancer in more than 80 per cent of cases.
Similar differences in the prevalence of S mitis and G adjacens were also found between the chronic pancreatitis samples and those of healthy people.
Although it is not clear whether the presence of certain species of bacteria are a cause or an effect of pancreatic cancer, the findings open up the possibility of developing a screening test for the disease, based on the levels of particular bacteria, the researchers said.