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Lymphoblasts from 93 children with acute lymphoblastic leukemia (ALL) were characterized by immunologic cell surface markers. These patients were treated on a single protocol, featuring adriamycin therapy during remission, and have been followed from 2 to 6.5 yr (median 4 yr). Three classes of patients were defined serologically: HTA+ Ia- CALLA-, Ia+ CALLA+ HTA-, and Ia+ CALLA- HTA-. Disease-free survival and sites of relapse were assessed within immunologic subsets. Similar to the findings of others, T-cell (HTA+ Ia-) patients fared poorly as compared to non-T-cell (Ia+ HTA-) patients (median disease-free survival was 12 and 47 mo. respectively; p = 0.0004). The majority of relapses in the HTA+ patients occurred at extramedullary sites. Late testicular relapse was rare among Ia+ patients. In addition, the "common ALL antigen" (CALLA) may identify a relatively favorable subset within the Ia+ population. The prognostic value of the immunologic markers was compared with traditional clinical factors. There was much overlap between HTA+, older age, and elevated WBC. However, neither age nor WBC alone were of prognostic significance among the Ia+ patients. We conclude that surface markers define both biologic and prognostic characteristics. The course of childhood ALL must be viewed in the context of homogeneous subsets and within particular therapeutic programs.
Sallan et al. (Sat,) studied this question.