Systematic review of pre-clinical chronic myeloid leukaemia.

BACKGROUND: Studies of a provisional entity pre-clinical chronic myeloid leukaemia (CML), which precedes chronic phase (CP) without leucocytosis or blood/marrow feature of CML CP, has been increasing.

OBJECTIVE: To perform a systematic review of pre-clinical CML and analysis the data relevant to disease progression to CML CP.

METHOD: We performed a literature search on 16 July 2017 using EBSCOhost Research Databases interface and Western Pacific Region Index Medicus. Two authors selected the studies, extracted the data and evaluated the quality of studies using an 8-item tool, independently. The outcomes were percentage of Philadelphia chromosome in the number of metaphases examined (Ph%), correlation between Ph% and blood count and time progress to CML.

RESULT: Our initial search returned 4770 studies. A total of 10 studies with a total 17 subjects were included. The lowest Ph%, which eventually progresses to CML, was 10%. Absolute basophil count seemed to correlate better with Ph% compared to total white cell and absolute eosinophil count. The time from the first documented pre-clinical CML to CML ranged from 12 to 48 months. The overall quality of the included studies was average.

CONCLUSION: This is the first systematic review on pre-clinical CML. This entity requires additional large-scale studies.