VTE Prevention With Rivaroxaban in Genitourinary Cancer Patients Receiving Systemic Therapy

Inclusion Criteria: * Patients who are starting systemic therapy for active GU cancer (bladder, testis, ureter/renal pelvis, kidney, urethral, penile) except for prostate cancer. * Age ≥ 18 * Eligible systemic therapies include chemotherapy, targeted therapies (tyrosine kinase inhibitors and antiangiogenic therapy), and immunotherapies. * Patients must be initiating systemic therapy with a minimum planned treatment duration of 8 weeks. Exclusion Criteria: * Anticoagulation (prophylactic or therapeutic dosing) required for another indication for entire duration of study * Known allergies to rivaroxaban * Concomitant use of dual antiplatelet therapy (two antiplatelet medications oncomitantly) * Ongoing refractory bleeding that may be exacerbated by rivaroxaban. * Concomitant use of strong inducers or inhibitors of CYP3A4 or glycoprotein-P (known interaction with rivaroxaban). * Severe renal insufficiency (Creatinine clearance \<30 mL/min (defined by Cockcroft-Gault)) * Severe liver disease (e.g. acute clinical hepatitis, chronic active hepatitis, cirrhosis) * Thrombocytopenia \< 50 x 109/L * Life expectancy under 6 months. * Pregnancy (if child bearing age under 50 and sexually active, documentation of use of effective contraception or negative B- HCG is required) * Patient is breastfeeding or lactating * History of condition at increased bleeding risk including, but not limited to: cerebral infarction (hemorrhagic or ischemic), active peptic ulcer disease with recent bleeding, spontaneous or acquired impairment of hemostasis in the previous 4 weeks. * Chronic hemorrhagic disorder * Inability to adhere to protocol or obtain consent. * Patients may be excluded from the study for other reasons, at the investigator's discretion.