Incidence and prognosis of cancer associated with bilateral venous thrombosis: a prospective study of 103 patients

Summary.  Background : A strong association between bilateral deep vein thrombosis (DVT) and cancer had been found in one retrospective study. To confirm this finding, consecutive patients with an objective diagnosis of bilateral DVT were followed over 12 months. Patients and methods : One-hundred and three patients, hospitalized for bilateral DVT, were included in the study. Twenty-six patients (25.2%) were already known to have a cancer, 26 (25.2%) had a previous history of venous thromboembolic disease, 44 (42.7%) had a symptomatic pulmonary embolism. The patients were scheduled to be prospectively followed up at 3, 6 and 12 months as outpatients. Information on recurrence, evidence of a new overt cancer and the cause of death were recorded for all patients. Results : A new cancer was diagnosed in 20 (26%) of the 77 patients without known cancer at admission. The risk of cancer was significantly more important in idiopathic thrombosis than in patients with secondary thrombosis (40.5% vs. 12.5%; odds ratio 4.8, 95% confidence interval 1.4, 18.8). Seventy percent of the cancers discovered had already spread. Age, gender, presence of pulmonary embolism, recurrence and location of the thrombosis were not statistically associated with the risk of cancer. The 1-year survival rates of patients with a previously known cancer and patients with a newly discovered cancer were, respectively, 26% and 35% ( P =  0.33). Conclusion : Bilateral DVT is a significant risk indicator of malignancy. Cancer is present in 45% of patients with bilateral DVT and is associated with a poor prognosis.