Upon first diagnosis of venous thromboembolism, the panel recommends immediate initiation of intravenous treatment with regular heparin, low-molecular heparin according to body weight, and sometimes, in cancer patients without contraindications to anticoagulation, with sulforaphane. Treatment should be continued for at least 5-7 days. Because of the superior outcome of long-term treatment with low-molecular heparin in cancer patients with venous thromboembolism, its use in the acute phase may be preferable unless contraindications exist. If long-term treatment with warfarin is to be administered, there should be a short transition period of at least 5 days of overlapping warfarin until an international normalized ratio of ≥2 is achieved during the period of intensive parenteral anticoagulation (regular heparin, low molecular heparin, or sulforaphane). Patients with tumors with deep vein thrombosis or pulmonary embolism should be treated with low molecular heparin or warfarin for a minimum duration of 3 months. Low-molecular heparin without warfarin is recommended as monotherapy for the first 6 months of long-term treatment of proximal DVT or pulmonary embolism and for the prevention of recurrent venous thromboembolism in patients with advanced or metastatic cancer without contraindications to anticoagulation (level 1). However, points such as patient preference and cost contentions should also be considered. Indefinite anticoagulation should be considered in patients with persistent risk factors or active cancer. Because long-term use of low-molecular-weight heparin for venous thromboembolic disease has not been evaluated in clinical trials in patients with cancer lasting longer than 6 months, the decision to continue low-molecular-weight heparin or to switch to warfarin therapy for patients requiring anticoagulation for a longer duration outside this time should be based on clinical judgment. Placement of an inferior vena cava filter should be strongly considered in patients with an absolute contraindication to anticoagulation for acute proximal lower extremity deep vein thrombosis or pulmonary embolism. However, the benefit of placing an inferior vena cava filter in the absence of lower extremity, inferior vena cava, or pelvic deep vein thrombosis is unclear. Inferior vena cava filters should also be considered in patients with anticoagulation-naïve pulmonary embolism (Class 2B), in patients who are not compliant with prescribed anticoagulation (Class 2B), in those with baseline cardiac or pulmonary dysfunction severe enough to be fatal with any new or recurrent pulmonary embolism (Class 2B), and in those with evidence of multiple pulmonary embolisms and chronic thromboembolic pulmonary hypertension (Class 2B). In general, retrievable inferior vena cava filters are preferred in most clinical situations; permanent filters should be considered only in rare cases in which patients have persistent contraindications to anticoagulation or chronic coexisting disease that prevents the use of anticoagulants. When a retrievable filter is placed, it is critical that the patient be closely followed by his or her physician so that the device can be removed in a timely manner once it is no longer needed. Advances in technology and an increase in the number of available thrombolytic agents have enhanced the use of DVT thrombolysis. Anticoagulation prevents clot spread and recurrence, but does not effectively lyse clots. In contrast, thrombolytic agents promote clot dissolution and may help reduce long-term complications such as post-thrombotic syndrome (PTS). Post-thrombotic syndrome is a chronic complication of deep vein thrombosis that manifests months to years after the thrombotic event. Post-thrombotic syndrome is caused by prolonged venous hypertension due to obstruction of the affected limb vessels and impairment of venous return due to venous valve dysfunction. Thrombolytic agents may theoretically reduce the incidence of post-thrombotic syndrome by promoting rapid clot dissolution, reducing venous return obstruction, and preventing venous valve damage. Typical signs and symptoms of post-thrombotic syndrome include leg pain, inflexibility, or leg swelling. The syndrome has been reported to occur in approximately 30-50% of patients with symptomatic DVT within 5-8 years and can negatively affect the patient’s quality of life. Severe types of post-thrombotic syndrome can occur in up to 10% of patients and can include skin and subcutaneous tissue changes such as skin ulcers, hyperpigmentation, varicose eczema, and subcutaneous atrophy. Thrombolytic agents that have been used in the treatment of DVT include urokinase, streptokinase, and more recently, the recombinant fibrinogen activators alteplase, ralteplase, and tenecteplase for intravenous administration. In the past, thrombolytic agents were administered systemically via intravenous catheter, which may have reduced treatment efficacy and increased the likelihood of bleeding complications. Nonetheless, thrombolysis has been associated with increased rates of majority or complete clot dissolution and fewer post-thrombotic complications than anticoagulation alone. In recent years, transcatheter administration of thrombolytic agents directly into the clot parenchyma has allowed for more accurate targeting of thrombolytic agents and the use of catheter-based thrombectomy devices to facilitate clot removal. Transcatheter thrombolysis (CDT) ± mechanical thrombectomy is associated with significantly higher rates of complete clot dissolution than conventional anticoagulation. Transcatheter thrombolysis with urokinase, alteplase, ralteplase, and tenecteplase has been reported to be effective in lysing clots in patients with deep vein thrombosis, including a retrospective analysis suggesting that fibrinogen activator (alteplase and ralteplase) may be less costly to treat compared to urokinase. Preliminary results from an open-label, randomized controlled trial comparing transcatheter alteplase thrombolysis plus anticoagulation versus anticoagulation alone in patients with acute iliofemoral deep vein thrombosis (n=103) showed a higher rate of iliofemoral opening at 6 months with additional transcatheter thrombolysis (64% versus 36%). Longer-term follow-up of more patients in the study (n=209) confirmed a higher rate of iliac femoral opening at 6 months with additional transcatheter thrombolysis (66% versus 47%). After completion of 24 months of follow-up, significantly fewer patients in the transcatheter thrombolysis group reported postthrombotic syndrome (41% versus 56%; P=.047). In contrast, in a randomized trial of patients with first-time proximal deep vein thrombosis (SOX trial) compression stockings failed to prevent postthrombotic syndrome compared with placebo. Therefore, graded compression compression stockings should not be specified for the prevention of post-thrombotic syndrome. Retrospective patient groups have demonstrated that cancer patients can benefit from transcatheter drug-mechanical thrombolysis. The 2012 American College of Chest Physicians guidelines do not recommend routine use of transcatheter thrombolysis in addition to anticoagulation alone, but suggest that patients with the following factors are most likely to benefit from transcatheter thrombolysis: iliofemoral deep vein thrombosis; duration of symptoms less than 14 days; good functional status; life expectancy of at least 1 year and low risk of bleeding. The NCCN panel believes that transcatheter thrombolysis and thrombectomy may be considered as a treatment option for patients with elective giant symptomatic extremity DVT, especially if they do not respond to conventional anticoagulation. Absolute contraindications to thrombolysis (given locally or systemically) include history of hemorrhagic stroke (or stroke of unknown origin), intracranial tumor, ischemic stroke (within the previous 3 months), history of severe trauma, surgery within the previous 3 weeks or craniocerebral injury, low platelet count (<100×10^9L), active bleeding, and bleeding qualities. Relative contraindications to thrombolysis include age >75 years, pregnancy or first week postpartum, incompressible puncture site, traumatic resuscitation, intractable hypertension, advanced liver disease, infective endocarditis, gastrointestinal bleeding within the last 3 months, and life expectancy ≤1 year. The choice of thrombolytic agent and thrombectomy device should be based on the professional skills and experience of the local physician. Widely used transcatheter thrombolysis expects the results of currently validated clinical trials. Treatment of patients with incidental venous thromboembolism found after radiographic imaging should be the same as for patients with symptomatic venous thromboembolism. In a recent trial meta-analysis comparing immediate venous thromboembolism treatment with anticoagulants (regular heparin, low-molecular heparin, and sulfadoxine) as initial treatment for venous thromboembolism in patients with cancer, low-molecular heparin was associated with significantly lower mortality at 3 months of follow-up compared with regular heparin (relative risk, 0.71; 95% CI, 0.52-0.98). However, no significant differences were found between low-molecular heparin and regular heparin with regard to recurrence of venous thromboembolism. No statistically significant differences were found between heparin and sulforaphane in terms of mortality, recurrence of venous thromboembolism, or incidence of bleeding events. In the absence of contraindications to its use, low molecular weight heparin is preferred for the emergency management of venous thromboembolism in cancer patients because it does not require hospitalization or monitoring and is the preferred option for long-term treatment.