Evaluation of Salivary Lactate Dehydrogenase Level as a Biomarker for Early Detection in Oral Cancer and Potentially Malignant Disorders: A Systematic Review and Meta-analysis

Introduction: Saliva diagnostics are emerging tools which are being explored as a non invasive method for early detection of oral premalignant lesions and Oral Cancer (OC). Salivary Lactate Dehydrogenase (LDH) is one such promising biomarker which has shown potential to be utilised in future for detection of premalignant lesions and conditions. The rationale behind this systematic review was to evaluate whether salivary LDH can be considered as biomarker for OC and Oral Potentially Malignant Disorders (OPMDs). Aim: To review the literature for levels of salivary LDH in patients with OC and OPMD. Materials and Methods: A comprehensive search was done and this systematic review was conducted in the Department of Oral Medicine and Radiology, Dr. DY Patil Dental College and Hospital, Pimpri, Pune, Maharashtra, India, following (Preferred Reporting Items for Systematic Reviews and Meta-analyses) PRISMA guidelines. The International Prospective Register of Systematic Reviews (PROSPERO) registration Identity Document (ID) was (CRD42022366117). Electronic data was searched through the database PubMed, ScienceDirect and Cochrane Library from 2012-2022. Observational and analytical studies, original longitudinal or case-control, randomised clinical trials, prospective controlled clinical trials with the inclusion of cases diagnosed with oral leukoplakia, Oral Lichen Planus (OLP), Oral Submucous Fibrosis (OSMF), OC and having salivary LDH levels reported were included. The data was collected from the studies that were included based on study design, eligibility criteria, histological differentiation, collection method, LDH level and the data were subjected to meta-analysis. Results: A total of 16 articles were included. The meta-analysis showed increased salivary LDH levels between cases with OC and Control Group (CG). The pooled estimate was 5.71 (95% CI: 3.89-7.53) with statistical significance of <0.05. In OSMF and controls the levels of salivary LDH was significantly increased. The pooled estimate was 30.38 (95% CI: 15.82-44.94) with statistical significance of <0.05. The level of salivary LDH among cases with premalignant lesions and controls was increased. The pooled estimate was 9.10 (95% CI: 3.45-14.75) with statistical significance of <0.05. In case of OLP and controls, the levels of salivary LDH were seen elevated. The pooled estimate was 6.76 (95% CI: 6.86- 20.38) with no statistical significance of p-value<0.05. Conclusion: To sum up, the results of this systematic review showed that levels of salivary LDH were higher in OC and OPMD patients than in healthy patients. Furthermore, the levels of salivary LDH are more in OC than OPMDs.