Inclusion Criteria:  Patients 18 years of age or older with a new or existing diagnosis of cancer and a CVC inserted in the last 72 hours.  Exclusion Criteria:  CVC in place for >72 hours Patient requires anticoagulation for other indication Concomitant use of dual antiplatelet therapy Major bleeding event in the last 4 weeks Patients receiving concomitant systemic treatment with strong inhibitors of both CYP 3A4 and P-gp (such as cobicistat, ketoconazole, itraconazole, posaconazole, or ritonavir). Pregnancy (documentation of use of effective contraception if sexually active or negative B- Hcg required) Severe renal insufficiency (Creatinine clearance <30 mL/min (defined by Cockcroft-Gault) in the previous 3 months Documented severe liver disease (eg. acute clinical hepatitis, chronic active hepatitis or cirrhosis) in the previous 3 months Known thrombocytopenia (platelet count < 50x 109/L) in the previous 3 months Allergy to rivaroxaban Life expectancy <3 months  History of condition at increased bleeding risk including, but not limited to:  a. cerebral infarction (hemorrhagic or ischemic), active peptic ulcer disease with recent bleeding, spontaneous or acquired impairment of hemostasis in the past 4 weeks. b. Chronic hemorrhagic disorder  Primary malignancy diagnosis of basal cell or squamous cell carcinoma of the skin Refused or unable to obtain consent