The relationship between salivary cytokines and oral cancer and their diagnostic capability for oral cancer: a systematic review and network meta-analysis.

BACKGROUND: Oral cancer (OC) is a common malignancy in clinical practice. Saliva testing is a convenient and noninvasive early diagnostic technique for OC. Several salivary cytokines have been identified as potential biomarkers for OC, including IL-8, IL-6, TNF-alpha, IL-1beta, and IL-10. Nonetheless, the optimal cytokine for OC diagnosis remains inconclusive and highly contentious. METHODS: PubMed, Embase, Web of Science, and Cochrane Library databases were comprehensively retrieved to collect all case-control studies on OC. A meta-analysis was performed to compare the levels of salivary IL-8, IL-6, IL-10, TNF-alpha, and IL-1beta in OC patients and healthy controls. Network meta-analysis (NMA) was carried out to probe into the accuracy of these salivary cytokines in diagnosing OC. RESULTS: This analysis included 40 studies, encompassing 1280 individuals with OC and 1254 healthy controls. Significantly higher levels of salivary IL-8, IL-6, TNF-alpha, IL-1beta, and IL-10 were observed in patients with OC in comparison to healthy controls. The results of NMA showed that TNF-alpha had the highest diagnostic accuracy for OC, with a sensitivity of 79% and a specificity of 92%, followed by IL-6 (sensitivity: 75%, specificity: 86%) and IL-8 (sensitivity: 80%, specificity: 80%). CONCLUSION: This study suggests that IL-8, IL-6, IL-10, TNF-alpha, and IL-1beta may be potential diagnostic biomarkers for OC. Among them, TNF-alpha, IL-6, and IL-8 are highly accurate in the diagnosis of OC. Nevertheless, further studies that eliminate other confounding factors are warranted, and more standardized procedures and large-scale studies are needed to support the clinical use of saliva testing.