Is the scoring system an effective clinico-biological tool in myeloid antigen positive adult acute lymphoblastic leukemia? Results of a long-term study.

Introduction: The classification and the clinical management of adult acute lymphoblastic leukemias (ALL) that co-express myeloid antigens (MyALL) remain controversial because of the confusion of terms and criteria to define these cases.

Materials And Methods: The characteristics of 112 adult ALL patients were reviewed. The scoring systems proposed by Catovsky and EGIL Group to classify MyALL were applied to qualify cases with score 0 (group I), 0.5-1.5 (group II) and 2 (group III).

Results: Forty-seven (42%) cases co-expressed MyAgs (group II: 29; group III: 18). A greater percentage of MyALL cases belonged to the earlier B and T subclasses. Ph+ incidence, WBC count and expression of CD34, CD45RA and CD25 were higher in group III. All patients received intensive therapy: out of these, 93 (83%) achieved CR. Although the response did not correlate significantly with the co-expression of MyAgs, the patients with the highest score had the lowest CR rate: 72, 83 and 86% in groups III, II and I, respectively. Surprisingly, the DFS curve of group III proved to be the most favorable. However, the OS was not significantly different, even if a worse curve was observed in group II. Multivariate analysis showed that only score 2 significantly affected DFS.

Conclusion: The scoring system accurately defines diagnosis and ontogeny of MyALL which appear to be related to incidence of Ph chromosome, elevated WBC count and elderly age. Consequently, fewer CR rates were documented in MyALL with the highest score. However, it was in this group that the good responders showed a greater capacity to continue in first remission.