Analysis of clinical characteristics and efficacy of chronic myeloid leukemia onset with extreme thrombocytosis in the era of tyrosine kinase inhibitors

The aim of this study was to investigate the clinical characteristics and efficacy of chronic myeloid leukemia (CML) onset with extreme thrombocytosis. A total of 121 newly diagnosed and untreated CML patients in chronic phase with complete clinical information from the First Hospital of Jilin University, from January 2010 to December 2014 were retrospectively recruited. Based on the platelet (PLT) count, 22 patients were assigned into CML with thrombocytosis (CML-T) group (PLT >1,000×109/L) and 65 patients were classified into CML without extreme thrombocytosis (CML-N) group (PLT ≤1,000×109/L). Fifty-four point five percent of patients in the CML-T group were female, which was higher than that in the CML-N group (27.7%) (P=0.022). Except for gender, there was no significant difference for clinical information of patients between the two groups. For Sokal and Hasford scoring systems, the percentage of patients at high risk in the CML-T group were higher than those in the CML-N group, 95.5% vs 52.3% (P=0.000) and 68.2% vs 41.5% (P=0.031), respectively; however, there was no significant difference for European Treatment and Outcome Study (EUTOS) score system between the two groups (P=0.213). In terms of major molecular response (MMR) rate, the percent of patients with MMR in CML-T group was lower than that in CML-N group at 36 months after tyrosine kinase inhibitor therapy (P=0.037). Up until December 2016, the median of event-free survival was 21 months in the CML-T group, however, that was not reached in the CML-N group (P=0.027). The majority of CML patients with extreme thrombocytosis were females, and compared to patients in the CML-N group, the percentage of high risk patients based on the Sokal and Hasford scoring systems was higher in the CML-T group, and the median event-free survival of patients was shorter.