Incidence and Time to Diagnosis of Secondary Malignancies Among Patients With Hairy Cell Leukemia: A Systematic Review and Meta-analysis.

Hairy cell leukemia (HCL) is a rare, indolent, chronic lymphoid neoplasm mainly treated with purine analogs. While some studies report an increased risk of secondary malignancies in patients with HCL, the incidence and the time from HCL diagnosis to the development of secondary cancers remain uncertain. To elucidate the incidence, we conducted a systematic review and meta-analysis. The cumulative incidence of secondary malignancies was 11.2% (95% confidence interval (CI): 8.6-14.3), with a higher incidence observed in patients treated with purine analogs (11.4%, 95% CI: 8.1-15.8) compared with those receiving non-purine analogs (4.8%, 95% CI: 3.6-6.3). The mean time from HCL diagnosis to secondary malignancy development was 100.6 months (95% CI: 56.1-145.0). The mean time varied by treatment group: 74.8 months (95% CI: 61.5-88.0) for non-purine analogs, 116.5 months (95% CI: 31.5-201.5) for purine analogs, and 86.6 months (95% CI: 64.2-109.0) for combination therapies. In conclusion, the choice of initial therapy significantly influences the risk of secondary malignancies, with purine analogs associated with a higher incidence.