Thrombosis, anticoagulation and outcomes in malignant superior vena cava syndrome

Anticoagulation is often used in superior vena cava syndrome (SVCS) associated with cancer (i.e malignant SVCS), even without thrombosis, but its effect on outcomes has not been reported. We aimed to determine factors and outcomes associated with thrombosis and anticoagulation in malignant SVCS. Patients with malignant SVCS diagnosed on computerized tomography (CT) were retrospectively included, indexed at diagnosis and followed for 6 months using medical records. The cohort included 183 patients with malignant SVCS of which 153 (84%) were symptomatic. Thirty of the 127 patients (24%) with a reviewable baseline CT had thrombosis of the SVC or tributaries at diagnosis. Patients with baseline thrombosis more often had symptomatic SVCS (p<0.01). 70% (21/30) of patients with thrombosis and 52% (49/97) of those without thrombosis at baseline received anticoagulation, most often at therapeutic doses. Thrombosis occurred in 5/39 patients with anticoagulation (13%) compared to 2/18 (11%) of those without, during follow-up (p=0.85). Anticoagulation was associated with a reduction in risk of SVC stent placement during follow-up that did not reach statistical significance (HR 0.47, 95% CI 0.2-1.13, p=0.09). Major bleeding occurred in 7 (4%) patients, six of whom received anticoagulation (four therapeutic and two intermediate dose). Neither thrombosis nor anticoagulation affected survival. Anticoagulation is commonly used as primary prevention but its benefit remains to be proven. The role of reduced-dose anticoagulation in non-thrombotic malignant SVCS should be prospectively assessed.