The expression of CD38 correlates with disease progression.

(A) When disease progression criteria were correlated with CD38 expression, the vast majority of CD38⁻ patients showed a strong tendency to maintain a stable disease (■). In contrast, most of CD38⁺ patients had a progressive disease (▪) as did a large proportion of patients belonging to the bimodal expression group. The differences among the 3 groups are highly significant (P < .001). (B) The strong tendency to develop progressive disease was not related to the percentage of CD38⁺ cells as shown by the analysis of CD38⁺bimodal expression patients divided according to the 30% positivity cutoff (< 30% and ≥ 30%).