Chronic myelogenous leukemia most often affects older people but it can occur in children and adolescents. However, how CML manifests and how it responds to treatment may be a little different in younger people.
An analysis of a European CML database found that an enlarged spleen was more common in young adults (younger than 30 years) compared to adults aged 30-59 years and older people (60 years or older) (Castagnetti and colleagues. Ann Oncol 2015; 26:185-192). For these three groups, the frequency of an enlarged spleen was 71%, 63% and 55%, respectively. Average spleen size was also larger in younger adults (mean 4.5 cm) compared to middle-aged (3.0 cm) or older adults (1.0 cm). A higher proportion of younger adults were considered to be at high risk of disease progression, in part because spleen size is one of the factors used to evaluate a person’s risk. The proportion of people at high risk of progression was 18% among younger adults, compared to 6% for older people. This risk was reflected in the higher rates of transformation from chronic-phase to progressive CML, which were 16% in younger adults compared to 7% in older adults.
A separate study also looked at CML in children and adolescents (Giona and colleagues. Br J Haematol 2015; epublished April 20, 2015). A total of 47 people were identified, and their median age at the time of diagnosis was 11-12 years. All received high-dose Gleevec.
Overall, about 90% achieved a complete cytogenetic response (CCyR) in the first six months of treatment. Two-thirds achieved a major molecular response (MMR, i.e. a 3-log reduction) in the first year of therapy, suggesting that their response to medication was similar to what is seen in adults. There were no CML deaths in younger people the first 4-5 years after diagnosis. During eight years of treatment, 60% showed no evidence of disease progression. Three people were able to stop Gleevec and maintained their molecular response. Twelve of 47 people (25%) underwent a stem cell transplant. The researchers concluded that high-dose imatinib appears to be very effective over the long term for children and adolescents with CML.