Salivary LDH in oral cancer and potentially malignant disorders: A systematic review and meta-analysis.

OBJECTIVES: To evaluate whether salivary lactate dehydrogenase (LDH) levels are increased in patients with oral cancer (OC) or oral potentially malignant disorders (OPMD) when compared to a healthy control group (CG). MATERIAL AND METHODS: We conducted a comprehensive search of specialized databases (PubMed/MEDLINE, The Cochrane Library, Web of Science, Scopus, and OpenGrey), including observational analytical studies evaluating the salivary LDH levels (in UI/L or µ/L) in OC or OPMD patients and compared them with a CG. RESULTS: Thirteen case-control studies were included. A total of 755 patients were evaluated, including 303 OC cases, 149 OPMD cases, and 303 controls. The meta-analysis showed that LDH levels were higher within the OC group than the CG (SMD 9.49; 95% CI 6.97-12; p = .00001). Patients with oral leucoplakia (SMD 11.67; 95% CI 1.01-22.33; p = .03) and oral submucous fibrosis (SMD 25.83; 95% CI -1.74-53.40; p = .07) also presented higher levels than the CG. In addition, OC patients had higher salivary LDH levels than oral leucoplakia patients (SMD 5.62; 95% CI 2.14-9.11; p = .002). Heterogeneity was high across all the evaluated studies. CONCLUSIONS: The determination of salivary LDH may be a useful method for screening and tracking OC and OPMD, but new protocolized studies are required to establish precise cutoff values.