Occult malignant neoplasm in patients with deep venous thrombosis.

An association between venous thrombosis and cancer was first suggested by Armand Trousseau and subsequently confirmed by multiple postmortem studies. In a previous study, patients with pulmonary embolism, as assessed by pulmonary angiography, were at significantly increased risk of occult cancer with a comparison group of patients without pulmonary embolism. This nonconcurrent prospective epidemiologic study extends these findings by demonstrating a significantly increased risk of occult cancer in patients with deep venous thrombosis (DVT) confirmed by impedance plethysmography as compared with those with suspected DVT in whom the diagnosis was ruled out. Differences in the incidence of malignant neoplasms were greatest within the first two years after the diagnosis of DVT, and patients younger than 50 years with venous thrombosis were at particularly increased risk of occult cancer (relative risk, 19.0). These findings indicate that all patients with DVT or pulmonary embolism should have an appropriate diagnostic workup and careful follow-up, particularly with regard to the risk of occult cancer.