Direct determination of chronic myeloid leukemia prevalence in Lombardy-Italy: Global implications.

Lombardy represents the largest region of Italy by population, with almost 10 million residents, a dimension similar to a medium size country like Sweden or Belgium. The CML subcommittee of the Lombardy Hematology Network (REL-CML) conducted a study at the beginning of 2023. Prevalence was calculated by direct input from the 21 centers participating in REL-CML. Tyrosine Kinase Inhibitors (TKI) prescription records collected from the ARIA regional registry were used to estimate the number of CML patients followed in smaller centers not participating in REL-CML. A total of 2285 patients were registered, representing a prevalence of 0.23 ‰. These data were compared to a similar census conducted in 2005, at the beginning of the TKI era, where a prevalence of 0.029‰ was calculated. This indicates that an almost 10 times increase took place during this period of time. Imatinib represents the most frequently prescribed first-line TKI; its use in 2022 still represented 75% of total first line prescriptions. An increased concentration of the care of CML patients in specialized REL centers with a decreased dispersion of patients in small centers was also evident over this 18 year period of time. Nineteen % of patients discontinued treatment, highlighting persisting logistical and biological challenges; one some recommendations on CML management are included to this aim.