Evaluation of salivary biomarker interleukin-6 in oral squamous cell carcinoma and oral potentially malignant disorders - A comparative cross-sectional South Indian study.

Background: Oral squamous cell carcinoma (OSCC) accounts for nearly 90% of oral malignancies and represents a major global health care problem. It is often preceded by oral potentially malignant disorders (OPMD). Although regular clinical examination forms the backbone for oral cancer screening, subtle lesions go unnoticed and there is a need for more sensitive and specific molecular biomarkers in mass screening of population. Salivary proteomics offer an attractive alternative to serum and tissue testing.

Aims: To find the diagnostic utility of salivary interleukin-6 (IL-6) in the differential diagnosis of OSCC, OPMD from healthy controls.

Study design: In vivo study.

Methods: After approval from the Institutional Review Board, unstimulated whole saliva was collected from 90 subjects, 30 in each group of OSCC, OPMD and controls after ethical clearance. Salivary IL-6 was measured by ELISA, and the results were statistically analysed.

Results: Significant difference in salivary IL-6 was seen between OSCC, OPMD and controls. Receiver operating characteristic curve analysis showed the highest area under a curve of 0.982 in distinguishing OSCC from controls. It showed a sensitivity of 71% and specificity of 100% at a cut-off value of 33.4 pg/mL (P = 0.000). Moderately differentiated OSCC (MDSCC) showed a significant increase in salivary IL-6 concentration compared to well-differentiated OSCC (WDSCC).

Conclusion: Results of the present study showed strong predictive power of salivary IL-6 in distinguishing OSCC from controls. Its levels also increased with tumor aggressiveness from WDSCC to MDSCC. Thus, salivary IL-6 could have a diagnostic and/or prognostic significance in identifying high-risk groups in mass screening of the population.