Incidence of Second Malignancies of Chronic Myeloid Leukemia During Treatment With Tyrosine Kinase Inhibitors

Background Tyrosine kinase inhibitors (TKIs) have revolutionized the treatment of chronic myeloid leukemia (CML) by providing patients with long-term survival. Although most patients who receive TKI treatment have shown satisfactory tolerance, second malignancies (SMs) should not be ignored because of lifetime treatment. We designed a retrospective study to evaluate the incidence and possible risk factors of SMs in CML patients treated with TKIs. Patients and Methods Records of 223 patients with Philadelphia chromosome-positive CML treated with imatinib were reviewed to investigate frequencies and characteristics of SMs. The data of SMs were compared with the number expected from the National Central Cancer Registry. The possible risk factors of SM in CML patients treated with TKIs were also evaluated using Poisson regression in this study. Results After a median follow-up of 64 months (range, 4-253 months) from CML diagnosis, 7 patients (3.14%) developed 6 different SMs including colon, stomach, breast, kidney, cervical, and lymphonodus tissue. The risk of second cancer was higher than expected (observed-to-expected ratio, 2.45; 95% confidence interval, 1.17-5.14; P = .018). No associated elements were found in terms of influencing the incidence of SM in CML patients treated with TKIs. Conclusion We found patients with CML treated with TKIs had a higher relative incidence of SM compared with the expected incidence among the general Chinese population. However, the correlations between second cancer and the potential risk factors including the length of exposure and cumulative dose of TKIs were not found in this study.