The Diagnostic Potential of Salivary Bacteria as Indicators of Oral Cancer

Objectives: To determine whether certain species of oral bacteria in saliva may be used as diagnostic markers for oral cancer. Methods: Unstimulated saliva samples collected by expectoration were taken from 42 oral cancer subjects and compared to 2 separate populations of 45 cancer-free subjects. All samples were evaluated for their content of 40 bacterial species using checkerboard DNA hybridization. The numbers of each species/ml were determined from saliva samples. Diagnostic sensitivity and specificity in detection of oral cancer by levels of salivary organisms were computed and comparisons made separately between the oral cancer population and the two control groups. Results: C. gingivalis showed the strongest association between salivary species and oral cancer. Analysis indicated that 91% of subjects with oral cancer were identified by having greater than 0.4x10⁵ /ml C. gingivalis (sensitivity). Specificity depended on the percentage of smokers in the control group. In age-matched control groups, specificity was between 91% (non-smokers) and 61% (smokers). Other species with diagnostic potential were similar between the two pairs of populations and included P. melaninogenica (sensitivity=specificity at 1x10⁵ = 66%), S. mitis.(sensitivity=specificity at 0.7x10⁵ = 61%) Conclusions: Determining levels of C. gingivalis in saliva may be a sensitive and specific means of diagnosing oral cancer. K23 DE-00453-03