A 51-Year-Old Woman Comes to the Office Due to 2

A 51-year-old woman comes to the office due to 2 days of progressive left leg pain and swelling.  She has had no trauma, fever, chills, chest pain, or shortness of breath.  The patient has a history of invasive ductal breast carcinoma treated with surgery and chemotherapy 2 years ago and was recently found to have brain metastases after a new-onset seizure.  She is undergoing brain radiation treatment and hormonal therapy for the cancer.
Temperature is 37.2 C (99 F) , blood pressure is 120/60 mm Hg, pulse is 84/min and regular, and respirations are 20/min.  Pulse oximetry shows 98% on room air.  Cardiopulmonary examination reveals no abnormalities.  There is left leg pitting edema and calf tenderness, but the right lower-extremity examination is normal.
Compression ultrasonography reveals an occluding thrombus in the left femoral vein.  Platelet count and coagulation studies are within normal limits.  Stool guaiac is negative.  MRI of the brain 2 weeks ago showed several 1- to 3-cm metastatic lesions in the right frontal and parietal lobes.
Which of the following is the most appropriate next step in management of this patient?

A) Catheter-directed thrombectomy followed by daily aspirin
B) Inferior vena cava filter placement and no anticoagulation due to risk of intracranial hemorrhage
C) Long-term anticoagulation therapy with low-molecular-weight heparin
D) Low-dose subcutaneous heparin only with close monitoring
E) Unfractionated heparin infusion followed by oral warfarin