Prognostic significance of serum lactic dehydrogenase levels and fraction of S-phase cells in non-Hodgkin lymphomas.

Sixty-four untreated patients with non-Hodgkin lymphomas (NHL) were analyzed with respect to fraction of S-phase cells in tumor material and serum lactic dehydrogenase (LD) levels. A significant correlation between the two variables was found in the low-grade (LGM) (r = 0.44, p < 0.01), but not in the high-grade (HGM) lymphomas. Shorter survival times were found for patients with tumors showing a high fraction of S-phase cells (> 4%) (p < 0.001) as well as for patients with elevated LD values (> or = 7.5 mukat/l) (p < 0.001). A multivariate analysis showed clinical stage (p < 0.001), S-phase fraction (p = 0.002) and age (p = 0.002) to be independent prognostic factors. For serum LD a borderline value (p = 0.05) was found, whereas morphology and B-symptoms were non-significant. LD level, but not fraction of S-phase cells, added prognostic information for LGM lymphomas (p < 0.001). For HGM lymphomas, the clinical stage was the strongest factor for prediction of prognosis. We conclude that the fraction of S-phase cells describes the biological behavior in a more reliable way than morphology (HGM vs LGM) and better identifies lymphomas with poor or good prognosis. The strong additional prognostic information obtained by serum LD within LGM lymphomas is assumed to be due to an association with the tumor burden.