Abstract:Objective To explore the sensitive immunocytochemical assay for disseminated tumor cells（DTC） in bone marrow of breast cancer patients. Methods First, the human breast cancer cell line MCF-7 was used as the specimen, and a mature immunocytochemical staining method (DAB method, APAAP method) was established. Then the human breast cancer cell line SK-BR3, MDA-MB 231 and SUM1315 were used as the specimen, adding cell lines to the mononuclear cells extracted from the peripheral blood of healthy people for detection to verify the sensitivity of the immunocytochemical staining method. Finally, the bone marrow specimens of patients with operable breast cancer were collected for clinical detection. Cytokeratin (CK) was selected as a tumor cell marker. The correlation between bone marrow micrometastasis and TNM staging of breast cancer was analyzed. Results Immunocytochemical methods (DAB method, APAAP method) were established to detect MCF-7 and other human breast cancer tumor cells. The sensitivity of DAB method and APAAP method for detecting tumor cells was that one tumor cell can be found in 1×10⁵ monocytes; DAB method was used to detect bone marrow samples of 34 patients with breast cancer, and there were DTC cells in the bone marrow of 6 patients, DTC was suspected in the bone marrow of 5 patients, and no DTC was found in the remaining 23 patients. The proportion of T2, T3 and N1, N2 and N3 stages in patients with bone marrow micrometastasis positive group was significantly higher than that in patients with bone marrow micrometastasis negative group (P<0.05). Conclusion In this study, a more reliable immunocytochemical detection method has established, which preliminarily indicates that it can be used to detect the presence of tumor cells spread in the bone marrow of breast cancer patients, and it is helpful to judge the prognosis of patients and guide individual treatment.