A simple screening method for the diagnosis of chronic myeloid leukemia using the parameters of a complete blood count and differentials

This study aimed to develop a simple and inexpensive method using the complete blood count (CBC) and differentials to screen for chronic myeloid leukemia (CML). The receiver operating characteristic (ROC) curves of each CBC parameter, differential and the neutrophil alkaline phosphatase (NAP) score using CML and non-CML cases were generated to determine effective cut-off values. They were applied to the review of randomly-selected 45,608 samples for validation. The leukocyte count showed the highest area under the ROC curve (AUC) value (0.909) among the CBC parameters. In the absolute counts of differentials, the AUC was the highest in basophils (0.982), followed by immature granulocytes (IGs) (0.975), which had cut-off values of 0.43 × 109/L and 0.46 × 109/L, respectively. The AUC of the NAP score was 0.963 at a cut-off value 122. In the validation, the absolute basophil counts were elevated in 280 samples from 96 cases, including 22 CML cases. In contrast, the absolute IG counts were elevated in 1310 samples from 516 cases, including only 17 CML cases. Three newly-diagnosed CML cases whose data were analyzed sequentially at the CML onset consistently met the basophil criteria before the IG criteria. The absolute basophil count is effective for screening for CML. •The ability of CBC, differentials and the NAP score to screen for CML was evaluated.•The absolute basophil count ≥0.43 × 109/L most effectively screened for CML.•The increase in basophils was proceeded by that of IGs at the onset of 3 CML cases.