Risk factors and clinical outcome of unsuspected pulmonary embolism in cancer patients: a case-control study

Background: Little is known about the risk factors and outcome of unsuspected pulmonary embolism (UPE) in cancer patients. Objectives: To assess the risk factors and outcome of UPE in cancer patients. Methods: The charts of 66 patients diagnosed with UPE were reviewed. Two control groups were selected: 132 cancer patients without pulmonary embolism (PE) and 65 cancer patients with clinically suspected PE. Variables associated with UPE were identified by multivariable analysis. Six-month survival and recurrent venous thromboembolism were compared by use of Cox proportional analysis. Results: Twenty-seven (40.9%) patients with UPE had symptoms suggesting PE. Adenocarcinoma (odds ratio [OR] 4.45; 95% confidence interval [CI] 1.989.97), advanced age (OR 1.18; 95% CI 1.021.38), recent chemotherapy (OR 4.62; 95% CI 2.269.44), performance status > 2 (OR 7.31; 95% CI 1.9028.15) and previous venous thromboembolism (OR 4.47; 95% CI 1.1617.13) were associated with UPE. When adjusted for tumor stage and performance status, 6-month mortality did not differ between patients with UPE and patients without PE (hazard ratio 1.40; 95% CI 0.533.66; P = 0.50). Patients with UPE were more likely to have central venous catheters and chemotherapy and less likely to have proximal clots than patients with clinically suspected PE. Recurrent venous thromboembolism occurred in 6.1% and 7.7% of patients with UPE and symptomatic PE, respectively. Conclusion: UPE is not associated with an increased risk of death. Patients with clinically suspected PE and those with UPE have similar risks of recurrent venous thromboembolism.