Objective: To evaluate serum lactate dehydrogenase (LDH) as a prognostic factor in previously untreated patients with multiple myeloma. Design: Study of 391 consecutive patients with uniformly treated multiple myeloma, followed until death in 63% of patients. Setting: Tertiary, referral cancer center. Patients: A total of 391 consecutive, previously untreated, symptomatic patients with various stages of multiple myeloma. Intervention: Various chemotherapy regimens that included doxorubicin or glucocorticoids, or both, with a consistent response rate (53%). Measurements: Outcomes included clinical response based on a 75% reduction of calculated tumor load and survival time from treatment. Univariate and multivariate analyses were used. Main Results: Eleven percent of patients showed a high serum LDH level of more than 5.0-mu-kat/L (300 U/L). An elevated LDH level was seen more frequently with a rise in the tumor load; an increased level was present in 26% of patients with high tumor mass. A high LDH level was associated with plasma cell leukemia or lymphoma-like clinical features (43%) and with plasma cell hypodiploidy (17%). Only 20% of patients with elevated LDH levels responded to chemotherapy compared with a response rate of 57% for patients with low levels of LDH. Using multivariate analysis, LDH was a significant independent predictor of response (P = 0.001), with an odds ratio of 0.25 (95% Cl, 0.11 to 0.57). A high LDH level was associated with a short median survival (9 months) and showed the highest relative risk (2.63; Cl, 1.75 to 3.95; P = 0.001). Conclusions: Elevation of the LDH level suggests the presence of occult extraosseous disease and high tumor mass. The LDH level is a predictor of a poor prognosis in selected patients who should be considered for early intensive treatment.
