Patients with cancer have a high risk of deep vein thrombosis which often develops in the veins of the lower limbs. The initial evaluation of clinically suspected deep vein thrombosis includes the estimation of the clinical probability by calculating risk scores such as the Wells score and the measurement of the D-dimer. However, the usefulness and accuracy of the clinical scores and d-dimer test are lower in patients with cancer who often undergo unnecessary (serial) ultrasonography.