Retrospective analysis of clinical factors affecting event-free survival in patients with chronic myeloid leukemia

Chronic myeloid leukemia (CML) is a myeloproliferative disease characterized by impaired and uncontrolled proliferation of mature or maturing granulocytes. CML is 15-20% of leukemias in adults. The prognosis of patients with CML has improved thanks to tyrosine kinase inhibitors used as first line initial treatment. The aim of this study was to identify the clinical characteristics of the patients with chronic myeloid leukemia at diagnosis and to examine the effects of these features on overall survival (OS) and event-free survival (EFS). Between January 2005 and June 2018, 224 patients with chronic myeloid leukemia who applied to Hacettepe University Hospital Department of Hematology and who were followed up with a diagnosis of chronic myeloid leukemia were included into our study. The clinical characteristics of the patients were obtained retrospectively from the hospital electronic record system. The duration of median follow-up was 75.13 (IQR: 39.4-126.8) months with the diagnosis of CML. At diagnosis; 204 (94.1%) of patients were in chronic phase; 9 patients (4.1%) were in acceleration phase and 4 patients (1.8%) were in the blastic crisis phase. The 6-year OS rate was 92.9% (95% CI: 89.1-96.7). At the time of diagnosis, the presence of> 5% blast in the bone marrow (p = 0.001), the presence of palpable spleen (p = 0.038), and the high Sokal risk score (p = 0.008) were defined as poor prognostic factors for overall survival. Hasford and EUTOS risk scores were not associated with overall survival. The 6-year EFS rate was 62.7% (95% CI: 52-72) in first line TKI therapy. Male sex (p = 0.003), the presence of > 5% blast in the bone marrow at diagnosis (p = 0.027), presence of thrombocytosis at diagnosis (p = 0.039), presence of palpable splenomegaly (p = 0.039), high Hasford Risk score (p = 0.015), high EUTOS Risk score (p <0.001) and cytogenetic unresponsiveness on 3rd month during treatment (p <0.001) have been identified as negatively factors on event-free survival. The relationship between the Sokal risk score and event-free survival in the first-line treatment was not established (p = 0.091). In the second-line TKI therapy, univariate analyses of EFS revealed that loss of complete hematologic response in the first-line TKI therapy (p = 0.018), optimum cytogenetic response (p = 0.002) on 3rd month and major molecular response (p =0.041) on 6th month during second-line therapy might be predictive for EFS. However, after multivariate analyses only cytogenetic response on 3rd month was significant (p = 0.007). No clinical factor affecting the event-free survival was found in the third-line TKI treatment. Comprehensive prospective studies are needed in patients with CML who are receiving third-line TKI therapy.