Prevalence and Significance of Asymptomatic Venous Thromboembolic Disease Found on Oncologic Staging CT

Carmel G. Cronin; Derek G. Lohan; Maccon Keane; Clare Roche; Joseph M. Murphy

Disclosures

Am J Roentgenol. 2007;189(1):162-170. 

In This Article

Abstract and Introduction

Abstract

Objective: The purpose of our study was to determine the prevalence of unsuspected venous thromboembolic disease-specifically, of pulmonary embolism (PE) and of inferior vena cava (IVC), iliac, and iliofemoral deep venous thromboses (DVTs)--in oncology patients on staging CT scans of the thorax, abdomen, and pelvis.
Materials And Methods: Retrospective analysis was performed on 435 consecutive staging CT thorax, abdomen, and pelvis scans performed on a variety of oncology patients for the presence of venous thromboembolic disease. The patient group consisted of 198 men and 237 women who ranged in age from 20 to 79 years (mean, 55 years). Disease type, stage, concomitant surgery or chemoradiation therapy regimes, anticoagulation status, and 6-month clinical and radiologic follow-up findings were recorded.
Results: We found a prevalence of 6.8% (23/339) unsuspected iliofemoral, 1.2% (4/339) unsuspected common iliac, and 0.3% (1/315) unsuspected IVC DVTs and 3.3% (13/397) unsuspected PEs occurring in patients with a wide range of malignancies. The overall prevalence of unsuspected venous thromboembolism (i.e., DVT, PE, or both) was 6.3% (25/397). DVT, PE, and venous thromboembolic disease were more common in inpatients (p = 0.002, 0.004, 0.023; relative risk [RR] = 1.6, 2.1, 1.4, respectively) and in those with advanced disease (p = 0.001, 0.01, 0.001; RR = 2.2, 1.8, 2.0, respectively).
Conclusion: Although there is a known increased risk of thromboembolism (DVT and PE) in oncology patients, many cases are not diagnosed, which can prove fatal. Staging CT simultaneously affords one sole investigation of the pulmonary, IVC, iliac, and upper femoral veins, thereby providing an important diagnostic opportunity. Assessment for DVT and PE is important when reviewing staging CT scans.

Introduction

Venous thromboembolism has an incidence of approximately one in 1,000 persons annually[1,2] and accounts for more than 250,000 hospital admissions annually in the United States.[2] Pulmonary embolism (PE) can be a fatal complication of deep venous thrombosis (DVT) from which more than 100,000 people die annually.[3] More than 90% of PEs arise from lower extremity DVTs.[2,4]

The true prevalence of venous thromboembolism is underestimated because many cases are not apparent clinically. It is estimated that by the time a proximal DVT is diagnosed, PE has already occurred in up to 50% of patients, but only 33-40% of those patients are symptomatic.[5,6] Malignancy and chemotherapy are independent risk factors and are associated with an increased incidence of venous thrombosis.[7] However, it is estimated that venous thrombosis is diagnosed in fewer than 40% of those with concomitant venous thrombosis and malignancy. Studies have shown that inadequately treated DVT is associated with recurrent PE.[8,9] When properly diagnosed and treated, clinically apparent PEs are an uncommon cause of death and recur in only a minority of patients.[10]

Unsuspected PE can be found in up to 1.5% of routine helical CT scans.[11] The incidence is higher in patients with malignancies, varying from 2.6% to 3.4%.[12,13,14] To date, the prevalence of unsuspected inferior vena cava (IVC), iliac, and iliofemoral DVT has not been reported. The purpose of our retrospective study was to review staging CT scans for evidence of thromboembolic disease--namely, for the presence of IVC; iliac; or iliofemoral DVT, PE, or both.

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