[Comparative study of cytogenetic response evaluated by conventional banding analysis and fluorescence in situ hybridization in chronic myeloid leukemia patients during tyrosine kinase inhibitor treatment].

Objective

To compare the cytogenetic response detected by conventional banding analysis (CBA) and fluorescence in situ hybridization (FISH) and to explore the correlation between the cytogenetic and molecular response in chronic myeloid leukemia (CML) patients during tyrosine kinase inhibitor (TKI) treatment.

Methods

CBA, FISH and real-time quantitative reverse transcriptase polymerase chain reaction (RQ-PCR) methods were performed to detect the cytogenetic and molecular response simultaneously in 504 bone marrow samples from 367 CML patients who received TKI treatment.

Results

Among 504 samples, 344 were detected to reach complete cytogenetic response (CCyR) by CBA, while 297 samples reached CCyR by FISH which were considered to carry BCR-ABL positive cells<1%. When the results of CBA, FISH and RQ-PCR were compared in 493 samples at the same time, it showed that in 337 samples with CBA-CCyR, 273 (81.0%) reached FISH-CCyR and 289 (85.8%) were BCR-ABL(IS) (International Scale, IS) ≤1% by RQ-PCR, compared to 9.0 (261/290) were BCR-ABL(IS) ≤1% among 290 samples with FISH-CCyR. There was no significant difference in the median value of BCR-ABL(IS) between samples in CBA-CCyR and FISH-CCyR (0.21% vs 0.13%, z=-1.875, P=0.061) . Furthermore, when the samples were divided into three groups according to BCR-ABL positive cells (0,>0~<1%, 1%~5%) by FISH, the statistical difference was observed, the proportion of samples with BCR-ABL(IS) ≤1% in the three groups were 94.1%, 57.6% and 27.7% respectively (χ(2)=43.499, P<0.001; χ(2)=9.734, P=0.003) , while the median value of BCR-ABL(IS) were 0.10%, 0.64% and 1.80% respectively (z=-5.864, P<0.001; z=-4.787, P<0.001) .

Conclusion

FISH results were in good concordance with CBA in identify samples in CCyR, FISH was more sensitive and had better correlation with RQ-PCR results than CBA, but how to define FISH-CCyR need further study.