Prevalence of unsuspected venous thromboembolism (VTE) on routine computed tomography (CT) scans in cancer patients.

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e19513 Background: Cancer patients have a 4-6 fold increased risk of venous thromboembolism (VTE) compared with the general population. Retrospective studies show a 1.5 to 6% prevalence of unsuspected VTE on routine imaging in cancer patients. The aim of this study was to prospectively determine the prevalence of unsuspected VTE in cancer patients undergoing routine staging CT and to evaluate factors predicting its occurrence. Methods: We administered questionnaires to 500 cancer patients who were scheduled for staging CT scans of the chest, abdomen and/or pelvis. Inclusion criteria were no history of PE or DVT or concurrent treatment with anticoagulants. Questionnaires ascertained demographics, medication history and concomitant symptoms. Two radiologists evaluated all CT scans independently and confirmed the diagnosis of VTE in consensus. Physicians were notified of their patient's diagnosis of unsuspected VTE. Fisher's exact test was used to examine differences between cases and controls. Results: Of the 500 patients evaluated, 6 did not meet the inclusion criteria and 13 did not complete the questionnaire; 481 were analyzed; 48.8% were female; mean age was 57.9 years. Twelve patients were diagnosed with unsuspected VTE: 2.4% (95%CI 1.0; 3.8); 9 had PE and 3 had iliac/femoral thrombi; 8 were women, mean age was 57.2 years. All VTE patients had a stage 3 or 4 solid tumor; 4 had colon cancer; 2 lung cancer. Four patients received treatment with bevacizumab, 3 with cisplatin and 2 with carboplatin. Comparing cases (unsuspected VTE) with controls, no differences were observed in age. Significant differences were observed with any chemotherapy (83.3% vs 26.5%, p<0.0001), bevacizumab (37.5% vs 6.4%, p<0.02), catheter use (50% vs 13.5%, p<0.003), abdominal pain (41.7% vs 11.8%, p<0.01). Following the diagnosis of unsuspected VTE, 6 patients received treatment (5 anticoagulation, 1 aspirin). Conclusions: Our study confirms the presence of unsuspected VTE in cancer patients undergoing staging CT. Concomitant treatment, catheter use and abdominal pain were related to unsuspected VTE. Not all patients were treated for their VTE, possibly reflecting the lack of clear guidelines to manage these patients. No significant financial relationships to disclose.