We performed a retrospective study to evaluate the incidence of second malignancies (SMs) in chronic myeloid leukemia (CML) patients treated with tyrosine kinase inhibitors (TKIs). We analyzed data from 339 patients with CML who were extracted from the CML Cooperative Study Group database. The standardized incidence ratio (SIR) was calculated to assess the risk of SMs using data from the Cancer Registries in Japan. The median follow-up was 65 months. SMs developed in 14 patients (4.1%, 10 men, 4 women) after the start of TKIs. The median age was 69 years at the time of the CML diagnosis and 72.5 years at the time of the SM diagnosis. Ten patients were treated with imatinib, three with dasatinib, and one with nilotinib as the initial treatment. The SIR for all malignancies was 1.05 (95% CI 0.50-1.93) for men and 1.08 (95% CI 0.29-2.76) for women. The difference in the overall survival (OS) of patients with or without SMs was not statistically significant (5-year OS: 82.5% vs. 92.9%; p = 0.343). A subgroup analysis of 166 patients treated with second-generation TKIs (92 dasatinib, 74 nilotinib) showed that the SIRs for all malignancies were 1.33 (95% CI 0.36-3.41) for men and 0 for women. In conclusion, the incidence of SMs in CML patients during TKI treatment was the same as that in the general Japanese population. There was no evidence of an increase in the incidence of SMs during second-generation TKI treatment. Furthermore, the occurrence of SMs during TKI treatment did not affect the survival or mortality in our cohort.
Keywords: Chronic myeloid leukemia; Second malignancies; Standardized incidence ratio; Tyrosine kinase inhibitor.