Certain types of mouth bacteria, some of which are found in gum disease, are associated with the development of pancreatic cancer, indicates a new study.

The finding, published in the scientific journal Gut, opens up the possibility of curbing the progress of one of the most difficult cancers to treat by altering the balance of bacteria, say the authors.

Pancreatic cancer -- which recently killed Apple computer founder Steve Jobs -- usually spreads very quickly, and only about one in 20 patients is still alive five years after diagnosis.

The authors base their findings on an initial comparison of the bacteria found in the spit of 10 patients with pancreatic cancer, which had not yet spread, and 10 healthy people, matched for age and sex.

They found significant differences between the bacterial colonies in the two groups, with 31 additional species and 25 fewer species in the spit of the cancer patients.

It is as yet unclear whether the presence of particular types of bacteria are a cause or effect of pancreatic cancer, say the authors. But their findings back previous research, which has implicated bacteria in the development of pancreatic diseases.

They go on to suggest that levels of certain bacteria could be used as a non-invasive and credible screen for pancreatic cancer, with the promise of earlier detection for a disease that has no clear symptoms in its early stages.