Salivary bacteria as indicators of oral cancer

Patients suffering from oral cancer have increased levels of certain bacteria in their saliva, according to research published in the Open Access journal, Journal of Translational Medicine. Six common species of bacteria were found at significantly higher levels in the saliva of patients with oral squamous cell carcinoma (OSCC) than in the saliva of healthy individuals. The researchers were able to use three of the six species as a diagnostic tool to predict more than 80% of oral cancer cases. These preliminary findings indicate that three species of bacteria may be incidentally or causally linked with OSCC, and if so detection of these species could be used as a simple, rapid and non-invasive saliva test to diagnose oral cancer.

In order to determine if the salivary microbiota in patients with OSCC would differ from that found in oral cancer-free individuals, Donna Mager and colleagues, from the Forsyth Institute and the Dana Farber Cancer Institute in Boston, collected saliva samples from 45 individuals diagnosed with OSCC and 229 controls. A computer then matched a subset of 45 members of the control group for age, gender and smoking with the 45 OSCC subjects. The saliva samples were then individually analysed for their content of 40 bacterial species using bacterial DNA probes.

Comparisons between controls and the 45 OSCC patients showed that six common bacteria - Prevotella melaninogenica, Capnocytophaga gingivalis, Capnocytophaga ochracea, Eubacterium saburreum, Leptotrichia buccalis and Streptococcus mitis - were found at significantly higher levels in OSCC patients compared with the controls. Three of these species of bacteria, C.gingivalis, P.melaninogenica and S.mitis, when used as diagnostic indicators of oral cancer, were found to correctly predict more than 80% of oral cancer cases.