Published by Oxford University Press on behalf of the European Society for Medical Oncology. All rights reserved. Background: The incidence of chronic myeloid leukemia (CML) increases with age, but it is unclear how the characteristics of the disease vary with age. In children, where CML is very rare, it presents with more aggressive features, including huge splenomegaly, higher cell count and higher blast cell percentage. Patients and methods: To investigate if after childhood the disease maintains or loses these characteristics of aggressiveness, we analyzed 2784 adult patients, at least 18 years old, registered by GIMEMA CMLWP over a 40-year period. Results: Young adults (YAs: 18-29 years old) significantly differed from adults (30-59 years old) and elderly patients (at least 60 years old) particularly for the frequency of splenomegaly (71%, 63% and 55%, P < 0.001), and the greater spleen size (median value: 4.5, 3.0 and 1.0 cm, P < 0.001). According to the EUTOS score, that is age-independent, high-risk patients were more frequent among YAs, than among adult and elderly patients (18%, 9% and 6%, P < 0.001). In tyrosine kinase inhibitors-treated patients, the rates of complete cytogenetic and major molecular response were lower in YAs, and the probability of transformation was higher (16%, 5% and 7%, P = 0.011). Conclusions: The characteristics of CML or the host response to leukemia differ with age. The knowledge of these differences and of their causes may help to refine the treatment and to improve the outcome.
