Prognostic significance of serum lactic acid dehydrogenase in Ewing's tumor of bone.

Pretreatment serum lactic acid dehydrogenase (LDH) levels were examined in 82 patients with Ewing's tumor of bone (23 metastatic and 59 localized). 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 (87 vs. 45%). After treatment with combined therapy, in this latter group the recurrence rate was significantly higher in patients with elevated serum LDH levels at admission than in those with normal serum LDH levels (50 vs. 9%). Of the 16 patients with localized disease who relapsed, 13 (81%) had elevated serum LDH levels at the time of recurrence. These results indicate that in Ewing's tumor serum LDH levels may serve as useful prognostic markers and could be valuable in monitoring the effectiveness of combined therapy.