Background: Saliva represents a promising non-invasive source of novel biomarkers for diagnosis and prognosis cancer. This meta-analysis evaluates the diagnostic value of salivary biomarkers for detection of malignant non-oral tumours to better define the value of saliva as an alternative liquid biopsy.Materials and methods: We performed a systematic review and meta-analysis. PubMed, Embase, LILACS and the Cochrane Library were searched to identify articles that examined the potential of salivary biomarkers for the diagnosis of malignant non-oral tumours. To assess the overall accuracy, we calculated the diagnostic odds ratio (DOR), area under hierarchical summary receiver operating characteristic (AUC) curve, sensitivity, specificity, positive likelihood ratio (PLR) and negative likelihood ratio (NLR) using a random- or fixed-effects model. Heterogeneity and publication bias were assessed. Statistical tests were two-sided.Results: One hundred fifty-five study units from 29 articles with 11,153 subjects were included. The pooled sensitivity, specificity, PLR, NLR, DOR and AUC were 0.76 (95% confidence intervals (CI), 0.74-0.77), 0.76 (95% CI, 0.75-0.77), 3.22 (95% CI, 2.92-3.55), 0.31 (95% CI, 0.28-0.34), 13.42 (95% CI, 12.28-15.96) and 0.85 (95% CI, 0.84-0.87), respectively.Conclusion: Salivary biomarkers may be potentially used for non-invasive diagnosis of malignant non-oral tumours.Key messagesThis meta-analysis evaluates the diagnostic value of salivary biomarkers for detection of malignant non-oral tumours to better define the role of saliva as an alternative liquid biopsy.Salivary biomarkers showed 85% accuracy for cancer distant to the oral cavity.Saliva represents a promising non-invasive source of novel biomarkers in cancer.
Keywords: Saliva; cancer; diagnosis; liquid biopsy; meta-analysis; salivaomics; salivary biomarkers.