Thursday, October 13, 2011

Spit bacteria could aid in cancer diagnosis

A new diagnostic tool works with spit of cancer patients, by focusing on the differences in bacterial composition when compared with healthy people. Researchers found that patients suffering from pancreatic cancer have a significantly different composition of bacteria in their spit, which could lead to a new method of diagnosis to discover this form of cancer. Diagnosing spit would have an advantage over conventional methods, as it is an easy, fast and non-invasive way of probing possible patients.

The researchers noted the difference when they compared ten patients with pancreatic cancer with ten healthy volunteers. They found a significant, all-round difference in bacterial composition of spit. When they consequently tested their method as a diagnostic tool, they found a sensitivity of 96,4 percent, which means that spit analysis revealed  96,4 percent of the patients having pancreatic cancer. In addition, the specificity was calculated as being 82,1 percent, which says that 82,1 percent of the people diagnosed with pancreatic cancer, actually have the disease. Taken together, the scores are pretty good, which is promising for the development of spit bacteria as a diagnostic tool.

In total, 31 bacterial species were found to be increased in patients with pancreatic cancer, while 21 bacterial species were less prevalent. In addition, two bacterial strains were found to be different between patients with chronic pancreatitis, which is an infection of the pancreas, compared with healthy volunteers. This shows that the bacterial differences might be useful for multiple diseases, and not just cancer.

Differences in bacterial composition can arise in disease because cells that comprise the 'wall' of the mouth, which are called epithelial cells, have a different structure. Because bacterial strains specifically recognize certain receptors on the cell surface, these cellular changes cause a change in bacterial strains that are able to bind, and thus exist, in the mouth. This accounts for the differences in observed bacterial composition when scientists perform a saliva swab on people.

A proper and fast diagnosis of pancreatic cancer is key to treating it. Currently, patients with the disease have a poor prognosis, leading it to be the fourth most common cause of cancer death worldwide. Though it is unknown whether differences in bacterial composition are an underlying cause of pancreatic cancer, it does seem like a useful characteristic for diagnostics.

Only last week, Apple founder and CEO Steve Jobs died, who was known to suffer from pancreatic cancer.

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