Secondary Prevention of VTE in Patients With Cancer and Catheter-Related Upper Extremity Deep Vein Thrombosis

Inclusion Criteria: 1. Adult patients (≥ 18 years old) with active cancer, defined as cancer (other than localized non-melanoma skin cancer) diagnosed or treated within 6 months, or the presence of metastatic, recurrent, or progressive malignancy, ongoing anticancer therapy, or hematological malignancy not in complete remission. 2. Objectively confirmed catheter-related upper extremity DVT and treated with any standard therapeutic anticoagulation (including LMWH dose reduction to 75% after the first month) for at least 3 months. 3. Able and willing to provide informed consent. Exclusion Criteria: 1. Active bleeding or other reasons for which anticoagulation is contraindicated. 2. Other indications requiring ongoing therapeutic dose of anticoagulation as deemed necessary by treating physicians (such as atrial fibrillation, mechanical heart valve, etc.). 3. Anticoagulation has been permanently stopped or reduced to prophylactic dose prior to enrollment for any reasons, except for participants who were transitioned to apixaban dosing regimen consistent with the protocol (2.5 mg twice daily) for ≤ 3 days . 4. Known contraindication for apixaban, such as allergy, hypersensitivity, or pregnancy. 5. Concomitant use of strong inhibitors or inducers of both cytochrome P450 3A4 (enzyme) and P-glycoprotein.