Rivaroxaban has been developed in the various clinical settings.Although cancer-associated DVT or PE was included in previously programs, limited patients of the total populations were cancer patients with totally implantable access ports in these studies. In this sense, investigators feel that new oral anticoagulants should be re-investigated in this highly specific patients group.Therefore, investigators are planning to conduct a prospective study to estimate the efficacy and safety of rivaroxaban for thromboprophylaxis in high-risk cancer patients with totally implantable access ports.

Eligibility Criteria:

1. Age 18-75 years;
2. Patients with malignant tumors who received implantable access ports for treatment;
3. Eastern Cooperative Oncology Group (ECOG) class 0-1;
4. will have a life expectancy > 3 months;
5. Expected survival of more than 6 months;
6. Khorana score ≥2 point.

Exclusion Criteria:

1. Patients with a history of allergies to rivaroxaban;
2. History of recent major or clinically relevant bleeding within the previous 4 weeks.
3. Patients with bleeding risks: thrombocytopenia (platelet count < 50*109/L), clinically significant active bleeding, active gastric ulcer disease, severe arterial hypertension, history of previous stroke; Inadequate renal function; creatinine clearance < 30 ml/min；
4. Inadequate hepatic function: aminotransferase > 3 times the upper limit of normal (ULN) (if liver metastasis, alanine aminotransferase > 5 times the ULN
5. Patients requiring strong cytochrome P450 3A4 (CYP3A4) inducers (rifampin, phenobarbital) or strong CYP3A4 inhibitors (HIV protease inhibitor, systemic ketoconazole) treatments.
6. Plan of treatment with bevacizumab or other anti-cancer drugs known to increase the bleeding risk.
7. Patients who have had anticoagulant drugs for any other reason.
8. Women who are pregnant or breastfeeding.