Lactate dehydrogenase as prognostic factor in limited and extensive disease stage small cell lung cancer - a retrospective single institution analysis

Purpose: The aim of this retrospective study is to present data on clinical significance of lactate dehydrogenase (LDH) serum levels in an unselected contemporary patient population with small cell lung cancer (SCLC) in limited disease (LD) and extensive disease stage (ED).

Patients and methods: From June 2004 to June 2008, our electronic database including all in-patient and out-patient contacts was searched for patients with newly diagnosed LD and ED SCLC. 397 cases were identified. We collected data on patient characteristics including clinical performance status and LDH serum levels, metastatic sites, efficacy of first line chemotherapy and survival.

Results: In both limited and extensive disease SCLC, elevated LDH serum levels resulted in significantly shorter median survival. The effect was most pronounced if levels were 300 U/l or higher. In patients with limited disease and normal LDH levels, median survival was 18.0 months. If LDH was higher than 300 U/l, overall survival was reduced to 12 months. In cases with extensive disease, overall survival was significantly lower in patients with elevated LDH serum levels with an additional reduction in overall survival in patients with LDH levels above 300 U/l. (7.0 vs. 12.0 months, p = <0.001). Multivariate Cox regression analyses revealed LDH levels to be an independent predictor of mortality after adjustment for age and Performance Status in LD and ED SCLC (HR 1.003, p = 0.017; HR 1.001, p = 0.002 respectively). However, categorizing LDH levels revealed no significant difference in LD SCLC.

Conclusion: In our contemporary comprehensive patient population, LDH is proved to be a strong, independent predictive factor of median survival in patients with LD and ED SCLC.