Monitoring a ‘metabolic shift’ after surgical resection of oral squamous cell carcinomas by serum lactate dehydrogenase

OBJECTIVES: Monitoring surgical removal of oral squamous cell carcinomas (OSCC) is being routinely performed through clinical and imaging follow-up. We analyzed the potential use of serum lactate, lactate dehydrogenase (LDH), and LDH isoenzymes (LDH 1-5) as biomarkers in blood for the monitoring of surgical removal of OSCC. MATERIALS AND METHODS: Serum lactate, LDH, and LDH isoenzymes (LDH 1-5) have been prospectively assessed in healthy individuals (n = 19), patients with OSCC (n = 34: primary OSCC, n = 32 and recurrent OSCC, n = 2) before surgery and after curative tumor resection (n = 26). LDHA and LDHB expressions were analyzed by immunohistochemistry (IHC) in the same OSCC tumor specimen. RESULTS: Positive LDHA tumor tissue expression measured by IHC (n = 34/34, 100%) was significantly associated with increased serum LDH-5 (n = 24/34, 71%, P = 0.0258) but weak significantly associated with increased total serum LDH (n = 23/34, 68%, P = 0.0592). Positive LDHB tumor tissue expression measured by IHC (n = 25/34, 74%) was significantly associated with increased total serum LDH (P = 0.0172). After surgery, serum LDH and LDH-5 isoenzyme significantly decreased and LDH-1 significantly increased in the aftercare. A significantly inverse correlation of LDHA with LDHB IHC scores was found (P < 0.0001). CONCLUSIONS: The association of LDHA and LDHB measured by IHC with serum LDH indicates that analyzing this enzyme could serve as a favorable 'liquid biopsy' (non-invasive diagnostic tool) for OSCC.