How long is long enough? Extended anticoagulation for the treatment of cancer-associated deep vein thrombosis.

A previously healthy 41-year-old man presents with left leg pain and shortness of breath. He has a 20–packyear history of smoking but quit 2 years ago. An ultrasound of the left leg shows thrombosis of the superficial femoral and popliteal veins.Onchest computed tomography (CT) angiogram, there is a large right hilar mass and enlarged mediastinal lymph nodes but no pulmonary emboli. He is treated with therapeutic doses of low–molecular weight heparin (LMWH), with brief interruptions for invasive procedures and surgery. Transbronchial biopsy is performed, and pathology yields a diagnosis of poorly differentiated non–small cell lung cancer (NSCLC; EGFR/KRAS wild type and ALK and ROS1 negative by fluorescent in situ hybridization). After additional tests, the patient is determined to have stage IIIA NSCLC. Subsequently, he receives concurrent chemotherapy consisting of cisplatin/etoposide and chest radiotherapy, resulting in a marked decrease in the size of the right hilar mass and mediastinal lymph nodes. He then undergoes right upper lobectomy and mediastinal lymph node dissection, which demonstrate no clinical or pathologic evidence of cancer. The patient returns to clinic, having been treated for >6 months with LMWH. He reports both mild shortness of breath with exertion and minimal chronic swelling of the left lower extremity. A follow-up ultrasound shows nonocclusive intraluminal thrombus in the left superficial femoral and popliteal veins; follow-up chest CT angiogram shows no evidence of pulmonary emboli.