e12602 Background: Chemotherapy is an important treatment strategy for breast cancer. Catheter related thrombosis (CRT) is one of the most common complications of catheterization, affecting patients’ living quality and survival. It is thus of great practical significance for exploring how to prevent CRT. That’s why we carried out this study to provide evidence-based medical data for the prevention and treatment of thrombosis in breast cancer patients. Methods: A prospective cohort study approach was adopted. Breast cancer patients who received deep vein catheterization chemotherapy from July 2021 to July 2023 were selected. Cohort A included patients in the treatment group: they received prophylactic anticoagulation after catheterization: Rivaroxaban, 10 mg, orally once/d for 2 months; cohort B included patients in the control group, who did not receive prophylactic anticoagulation. The thrombosis was compared between the patients in the two groups within six months after catheterization. The comparison between groups was tested by X2 test, and logistic regression analysis was used to analyze the influencing factors of CRT. Results: A total of 402 breast cancer patients were enrolled. The incidence of CRT was 2.0% (4/201) in the treatment group of 201 cases and 12.4% (25/201) in the control group of 201 cases ( P=0.000). The thrombus was mainly located around the axillary vein, basilic vein and subclavian vein, the innominate vein, and the internal jugular vein. There were 44.8% (13/29) patients developed CRT within 30 days after catheterization, 20.7% (6/29) patients developed CRT within 30~<60days, and 34.5% (10/29) patients developed CRT within 60~<120 days. Patients diagnosed with CRT received anticoagulant therapy for 3 months. Within three months, the thrombus regression rate reached 100.0% (29/29). Univariate analysis showed that whether to receive prophylactic anticoagulation, whether hemoglobin is normal, patients whether to experience previous endocrine therapy, different Age group and chemotherapy regimens were actors for thrombosis, P<0.05 respectively. Multivariate analysis indicated that age and whether to receive prophylactic anticoagulation were independent factors for thrombosis ( P=0.019, P=0.006, respectively). Patients diagnosed with CRT received deep vein cannulation while anticoagulation therapy was administered, with smooth infusion. They all completed antitumor therapy as planned, and no abnormalities such as new thrombosis and pulmonary embolism were found. Conclusions: The prophylactic anticoagulation regimen with Rivaroxaban can reduce the incidence of CRT in breast cancer, showing good efficacy and safety. Therefore, medical staff should carry out early prevention, early detection and early treatment for CRT to improve the living quality of patients. Clinical trial information: ChiCTR2000031649.