Fluorescence in situ hybridization on peripheral-blood specimens is a reliable method to evaluate cytogenetic response in chronic myeloid leukemia.

PURPOSE: To evaluate the usefulness of fluorescence in situ hybridization (FISH) on peripheral-blood specimens to evaluate the cytogenetic response to treatment in patients with chronic myeloid leukemia (CML). PATIENTS AND METHODS: In a first attempt, we analyzed 62 bone marrow specimens using interphase FISH and compared the results with those of conventional cytogenetics. In a second step, we analyzed 60 paired sets of bone marrow and peripheral-blood specimens with interphase FISH. RESULTS: The results of interphase FISH agreed with conventional cytogenetics on bone marrow for most patients, and only minor differences were found (r =.98). The comparison of interphase FISH on bone marrow versus peripheral-blood specimens showed a strong correlation between these two specimen sources (r =.97). CONCLUSION: Our results confirmed that FISH is a sensitive technique for the evaluation of response to treatment in patients with CML. Moreover, our study suggests that follow-up of cytogenetic response to therapy can be evaluated on peripheral-blood specimens, thus enabling an easier and more frequent evaluation of patients. The next step will be to evaluate this technique in a large prospective trial to define the prognostic value of complete remissions evaluated by FISH.