Detection of disseminated tumor cells in the bone marrow of breast cancer patients with a new molecular method

Abstract

Objectives: Numerous studies have shown that the presence of clinically occult disseminated tumor cells (DTC) in the bone marrow (BM) of breast cancer patients is associated with an unfavourable clinical outcome. Immunocytochemistry (ICC) remains the gold standard for their detection. Assays based on RT-PCR are available; however, so far they have not been used for routine detection of DTC. Therefore, the purpose of this study was to evaluate a newly established molecular method for the detection of DTC. Materials and methods: BM aspirates from 405 patients were examined. Half of the samples were immediately inserted into ICC and the other half was examined with our newly established molecular method based on RT-PCR. Immunocytochemistry was performed according to the Consensus Recommendations of the German, Austrian, and Swiss Societies of Senology and ISHAGE Working Group (A45B-B3 antibody). RT-PCR was conducted as a one-step real-time assay. Cytokeratin 19-mRNA was amplifi ed. Results: In 142 of 405 (35%) aspirates disseminated tumor cells were detected by RT-PCR. In 34% of patients DTC were detected by ICC. 48% of the BM samples were positive by at least one method. In 73% of the patients identical results were obtained (p<0,001). Conclusion: Our newly established molecular assay for the detection of disseminated tumor cells, and thus minimal residual disease, is sensitive, fast and reproducible, and has a potential to be used as a confi rmatory or alternative test for DTC detection.