Serum lactate dehydrogenase (LDH) as a tumor marker in Ewing's sarcoma.

The pretreatment serum lactic acid dehydrogenase (LDH) level of 246 patients with Ewing's sarcoma of bone (47 metastatic and 199 localized at presentation) was examined to evaluate the use of LDH as a tumor marker. The percentage of patients with increased serum LDH levels was significantly higher in the metastatic group than in the group of patients with localized disease (83% vs 41%; p less than 0.01). In the latter group the relapse rate after treatment with combined therapy was significantly higher in patients with an elevated serum LDH at admission than in those with normal serum levels (68.2% vs 39.3%; p less than 0.01). After local treatment, in 73 out of 82 patients with an elevated serum LDH at admission the enzyme level normalized whereas in 9 it fell but never reached a normal value. The rate of relapse in these two groups was respectively 64% and 100%. The value of serum LDH at the time of recurrence, determined in 62 patients, was elevated in 50 (80.7%). These data demonstrate that in Ewing's sarcoma of bone pretreatment serum LDH levels have a definitive value in establishing the prognosis and could also be used in evaluating the response to therapy. A persistent elevated value of serum LDH, or an increasing value after a transient normalization, is usually followed by relapse.