Serum lactate dehydrogenase level in patients with nasopharyngeal carcinoma.

Serum lactic dehydrogenase (LDH) levels of 465 patients with nasopharyngeal carcinoma (NPC) were assayed retrospectively. Four cohorts were selected in order to investigate the enzymes: 1) stage IV disease (118 cases) with pretreatment measurement, 2) relapse cases (159 cases) with pretreatment measurements, 3) no evidence of disease (217 cases) with spotting or serial measurements, and 4) monitoring of response to cytotoxic chemotherapy (34 cases). Higher serum LDH levels and more cases with elevated values were found in metastatic disease, especially relapse cases with liver and/or multiple organ site metastases. Serum LDH levels in locoregional disease were rarely found to be greater than two times the normal level. The value of serial serum LDH measurement for detecting disease relapse in the follow-up of patients with NPC is limited. Twelve percent of cases with no evidence of disease demonstrated elevation in serum levels. Serum LDH levels were found to correlate with the clinical responsiveness to systemic chemotherapy. Cases with normal serum LDH before treatment had a better chance of survival than those with elevated levels (median: 53 vs. 10 months, p = 0.008).