Abstract: OBJECTIVE To investigate the diagnostic value of peripheral blood thrombomodulin(TM), tissue factor(TF) and calcitonin gene-related peptide(CGRP) in breast cancer patients undergoing chemotherapy for catheter-related bloodstream infection(CRBSI), and to analyze the correlation with the degree of infection.METHODS A total of 475 breast cancer patients in Affiliated Hospital of Nantong University from Jun 2017 to Dec 2019 were recruited in the study. Among them, 62 cases with CRBSI were divided into the CRBSI group, and 413 cases without CRBSI were in the N-CRBSI group. The peripheral blood levels of TM, TF, and CGRP were compared between the two groups. Multivariate Logistic regression analysis was used to analyze the influencing factors for CRBSI in breast cancer patients after chemotherapy. The receiver operating characteristic curve(ROC) was used to analyze the diagnostic value of peripheral blood TM, TF, and CGRP levels for CRBSI after chemotherapy in breast cancer patients. The levels of TM, TF, and CGRP in peripheral blood of patients with different degrees of infection were analyzed. Pearson analysis was used to analyze the correlation between the levels of TM, TF, and CGRP in peripheral blood and the degree of infection.RESULTS Age, catheter indwelling time, catheter maintenance cycle, catheter movement, catheter material, parenteral nutrition, combined with underlying diseases and peripheral blood TM, TF, CGRP levels were all factors influencing the incidence of CRBSI after chemotherapy in breast cancer patients(P＜0.05). The AUC of the combination of of TM, TF, and CGRP in the diagnosis of CRBSI in breast cancer patients after chemotherapy was 0.897, with a sensitivity of 98.39% and a specificity of 70.98%, which was significantly higher than those of any single index(P＜0.05). There were significant differences in the levels of TM, TF, and CGRP in the peripheral blood of patients with different degrees of CRBSI infection after breast cancer chemotherapy(P＜0.05). Peripheral blood TM and TF levels were positively correlated with the severity of infection, and CGRP levels were negatively correlated with the severity of infection(P＜0.05).CONCLUSION Indexes of TM, TF, and CGRP have diagnostic value for CRBSI in breast cancer patients after chemotherapy. The levels of TM, TF, and CGRP are closely related to the degree of CRBSI infection, which can have guiding significance for clinical prediction of the severity and prognosis of CRBSI patients after breast cancer chemotherapy.