As the probability of survival of patients with chronic myelocytic leukemia (CML) gradually decreases over a period of 10 years, long-term follow-up is mandatory. Between 1977 and 1994, 68 children and adolescents between 1.0 and 18 years of age with CML in chronic phase and 7 presenting with blast crisis at diagnosis were reported to the study center in Münster. The Philadelphia-chromosome and/or BCR/ABL rearrangement could be detected in 66 children. The 4 Philadelphia-negative patients and 5 patients without karyotyping fulfilled the morphological criteria of CML. Clinical symptoms and hematological findings at presentations were similar to adult patients.
Therapy: Until 1985 chemotherapy consisted predominantly in busulfan (BU), later in hydroxyurea (HU) or a combination of both and since 1987 increasingly in HU plus interferon-alpha. 47 patients (6 in blast crisis) were allografted once or twice (n = 4) (27 HLA-identical, 16 unrelated, 4 haplo-identical) within 2.3-135 months (median 12 months) after diagnosis.
Results: 38 of 75 patients (3 in blast crisis at diagnosis) were alive after a median follow-up of 5.5 years. The probability of 12 years survival was 27%, SE 9% for patients in chronic phase. All deaths (n = 19) were leukemia-related in the 27 non-transplanted children. A comparison of survival for patients with or without bone-marrow transplantation (BMT) showed a significant difference in favour of the BMT-group (42%, SE 13% vs. 10%, SE 8%, p log-rank 0.003). The probability of survival increased to 62%, SE 10%, if patients transplanted later than 3 years after diagnosis were excluded. Only few patients (4/39 with information about the cause of death = 10%) died due to recurrent CML after BMT.
Conclusion: Our data confirm the unfavourable outcome of CML in pediatric patients if treated with chemotherapy alone. With early BMT high cure rates can be achieved. If transplant-related mortality which in our patient group was 21% (8/39) can be reduced, even a higher cure rate appear realistic for the future.