Purpose: Mantle cell lymphomas (MCLs) represent a clinically aggressive lymphoma subtype with a poor prognosis. To explore a potential progress in outcome a historical comparison was performed using data from the Kiel Lymphoma Study Group (KLSG; 1975 to 1986) and the German Low Grade Lymphoma Study Group (GLSG; 1996 to 2004).
Patients and methods: All patients with the histologically confirmed diagnosis of advanced-stage nonblastoid MCL were eligible. To minimize the potential heterogeneity of different risk profiles frequency matching was pursued. In addition, we adjusted for potential confounding variables by multiple Cox regression.
Results: A total of 520 patients were assessable, 150 from KLSG and 370 from GLSG studies. The median overall survival was 2.7 years for KLSG patients as compared with 4.8 years for GLSG patients (P < .0001). The 5-year survival rates were 22% in the KLSG group (95% CI, 13% to 31%) as compared with 47% for GLSG treated patients (95% CI, 38% to 55%). The hazard ratio adjusted for performance status, lactate dehydrogenase, and age was 0.44 for GLSG patients (95% CI, 0.32 to 0.59).
Conclusion: Median overall survival of patients with advanced nonblastoid MCL almost doubled during the past 30 years. Potential reasons for this apparent improvement in overall survival include the application of anthracycline-containing regimens and new approaches, such as antilymphoma antibodies or stem cell transplantation. Advances in general supportive care, new diagnostic tools, and general improvement of life span might have also reinforced this effect. However, our results are questioning the validity of historical comparisons which had been frequently applied in previous trials.