Abstract

Background: The course of chronic lymphocytic leukemia (CLL) is highly variable. Therefore, there is a need for prognostic factors that are readily performed and have a high predictive power.

Methods: The occurrence of translocations, a recently identified prognostic factor in CLL (

Blood
2006
;
107
:
742
–751
), was studied in 148 previously untreated, mostly early-stage patients and compared with respect to treatment-free survival (TFS) to several prognostic factors (Binet stage, mutational status of immunoglobulin genes, CD38, thymidine kinase serum concentration and cytogenetic aberrations detected by interphase FISH). To investigate chromosomal translocations, we applied a new method, CpG oligodeoxynucleotide stimulation that allows efficient preparation of metaphase spreads from CLL cells.

Results: The occurrence of translocations classified the majority of patients with poor prognosis. If translocations were investigated in addition to the currently used prognostic factors they identified those patients who were classified to be in a low-risk group based on traditionally used criteria, who had in fact a high risk for progression. Vice versa, patients in the high-risk groups for progression who did not have translocations had a long TFS. There was a substantial overlap of patients who had translocations and additional risk factors. But when we omitted patients who had translocations in addition to a given risk factor, we found that the respective risk factor lost its prognostic significance for the remaining patients. The two factors that retained their prognostic power in these patients were translocations and the Binet stage. This could suggest that the prognostic significance of the currently used factors derives from their frequent co-occurrence with translocations. Finally, multivariate analyses demonstrated that Binet stage (p=0.02) and translocations (p=0.0005) are the factors with the highest impact on TFS in our study cohort.

Conclusion: We present a method for efficient preparation of metaphase spreads in CLL cells in order to investigate chromosomal translocations. The occurrence of translocations is an independent prognostic marker in CLL. Finally, translocations occur not as a late event in the course of the disease and may define a new biological subgroup in this disease entity.

Disclosure: No relevant conflicts of interest to declare.

Author notes

*

Corresponding author