Objective  This study was purposed to raise awareness of chronic myelogenous leukemia(CML)caused by benzene, so as to strengthen prevention and standard treatment.

  Methods  A retrospective analysis was made on the history of benzene exposure, clinical characteristics, diagnosis and treatment process and outcome of 5 patients with CML caused by benzene from 2009 to 2020.

  Results  The median age of onset of 5 patients was 35(28-41)years old, the median benzene exposure time was 6(4-10)years, and the median latency time was 6(4-10)years. There were no strict personal protections at work. The main clinical manifestation was fatigue, and the ECOG scores were 0-1. Mild splenomegaly occurred in 4 cases. The peripheral blood was obvious high in leukocytes and normal in platelets. All patients were diagnosed as CML in chronic phase and classified as low-risk groups by Sokal score. These patients all took the tymsine kinase inhibitor(TKI). The median time from diagnosis to the initiation of TKI treatment was 11(1-29) months, and the median time of total TKI treatment time was 8(6-10)years. Complete hematological response(CHR)was achieved in all patients at 3 months, including 3 cases with early molecular response(EMR), complete cytogenetic response(CCyR)at 6 months, and major molecular response(MMR)at 12 months. However, during the long-term medication and follow-up, only one patient achieved deep molecular response, and the patients who did not get deep molecular response failed to meet the withdrawal criteria and could not achieve treatment free remission after withdrawal.

  Conclusions  There are various types of leukemia caused by benzene, but CML is rare. Once the diagnosis is confirmed, treatment should be standardized as soon as possible, including early application of TKI, and long-term strict follow-up is necessary.