Background and objectives: To investigate whether CD38 expression at diagnosis is an independent predictor of survival and assess its associations with other clinical parameters used in the staging of B-cell chronic lymphocytic leukemia (B-CLL).
Design and methods: CD38 expression was analyzed in 155 consecutive unselected patients newly diagnosed with B-CLL from January 1991 to July 1997. In all cases CD38 expression was evaluated at diagnosis and patients were classified into two groups: those with > or = 30% were considered positive (CD38+) and those with < 30% were considered negative (CD38-). Statistical differences between each group were analyzed using c2 tests for categorical variables and Student's t-tests for continuous variables. Survival analysis was performed at the univariate level by the Kaplan Meier technique and at the multivariate level by Cox hazard models.
Results: Thirty (19%) patients were CD38+. CD38+ was associated with atypical morphology (p=0.004), a diffuse bone marrow pattern (p=0.016), Rai stage > or =2 (p=0.009), high lactate dehydrogenase (p=0.02), high b2 microglobulin (p=0.004), and higher lymphocyte count (p=0.02). Furthermore, CD38+ patients required treatment more frequently (p=0.006) and CLL-related mortality was significantly higher (p=0.012). When we divided the study group into patients with Rai 0-1 and Rai 2-4 stages, CD38 positivity was only significantly associated with mortality in the early stage patients (p= 0.012 vs p= 0.68). CD38 expression in the multivariate analysis lost its statistical significance. None of these results was modified when the CD38 cut-off was set at 20%.
Interpretation and conclusions: CD38 expression identifies a subgroup of B-CLL patients with aggressive clinical presentation and worse outcome. Its expression is probably associated with other prognostic factors, but the feasibility of determining this parameter makes it easily reproducible and adds prognostic information at diagnosis to aid prediction of the clinical course and outcome of B-CLL.