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

Results

The groups consisted of 232 patients with early stage disease and 203 with advanced stage disease. Disease types included lymphoma, n = 74; breast carcinoma, n = 82; lung cancer, n = 43; gastrointestinal malignancy (esophageal, gastric, small and large bowel, pancreatic cancer, hepatocellular, and biliary), n = 126; urinary tract carcinoma (kidney, bladder, and testicular), n = 44; gynecologic malignancies (ovarian, endometrial, and cervical cancer), n = 34; melanoma, n = 17; and other types of cancer, n = 15. None of the outpatients was on any form of anticoagulation therapy.

Scans were obtained before the initiation of chemotherapy in 89 patients, during chemotherapy or an interim treatment in 234 patients, and at follow-up when patients were not undergoing any cancer treatment in 112 patients. Determining the presence of a PE was not confounded by another lung disease in any of the patients. No obstructing or compressing abdominal masses that would contribute to DVT formation were present.

Twelve examinations were initially excluded because of a known or suspected DVT within the prior 12 months as determined by reviewing the radiology records. In the remaining 435 examinations that were reviewed, 38 scans (8.7%) were excluded from the evaluation for PE because of poor opacification or excess respiratory motion. The examinations of 96 patients (22%) were excluded from the evaluation for iliofemoral or iliac DVT because of poor opacification or the presence of streak artifact or metallic artifact. Therefore, 397 patients met the inclusion criteria for PE assessment and 339 patients met the inclusion criteria for DVT assessment.

Of the 435 patients, 179 were inpatients and 256 were outpatients. After excluding the nondiagnostic scans, 133 of the 339 patients assessed for DVT were inpatients and 206 of the 339 were outpatients; 177 of the 397 patients assessed for PE were inpatients and 220 of the 397 were outpatients ( Table 1 ).

Of the 339 patients being evaluated for DVT, we found that 23 (6.8%) had unsuspected iliofemoral DVT and four (1.2%) had common iliac vein involvement. One of 315 patients (0.3%) evaluated had an IVC DVT, and 13 of 397 patients (3.3%) evaluated had an unsuspected PE (Figs. 1A, 1B, 2A, 2B, 2C, 2D, 2E, 3A, 3B, 3C, 3D, and 3E). The overall prevalence of unsuspected venous thromboembolism (i.e., DVT, PE, or both) in this group undergoing staging CT of the thorax, abdomen, and pelvis was 6.3% (25/397). Table 2 outlines the demographics (patient sex, patient age, diagnosis, treatment, thromboembolism site) of the 25 patients with positive findings for unsuspected venous thromboembolism.

Figure 1.

Figure 2.

Figure 3.

Table 3 outlines the location of the DVTs and PEs and patient characteristics. It highlights the positive venous thrombosis results according to site, number, distribution per disease, inpatient and outpatient status, presence and absence of treatment, and early and advanced stage of disease.

All cases of iliofemoral DVT and of iliac DVT showed intraluminal filling defects and two had mural components. None of these patients was on therapeutic anticoagulation at the time of scanning. Fewer than 15% of the inpatients were taking a prophylactic dose of tinzaparin sodium (Innohep, Pharmion).

Patients with advanced disease were more likely to have a DVT or PE, occurring in 8.9% (18/203) of the patients with advanced stage disease; 48% (11/23) of patients with an unsuspected DVT had an unsuspected PE.

Table 4 shows the logistic regression analysis results for DVT (chi-square value of 33, degrees of freedom [df] = 6, p = 0.001, n = 339, -2 log likelihood value = 129). Inpatients with a carcinoma were more likely to have a DVT than outpatients (p = 0.002, odds ratio [OR] = 4.8). Those with high-stage disease were significantly more likely to have a DVT than those with a low-stage disease (p = 0.001, OR = 6.3). Patient age, treatment status (receiving or not), and disease type (hematologic, solid organ, or breast) were associated with an increased risk of DVT; however, this finding did not reach statistical significance. Patient sex was not associated with an increased risk of DVT; this finding is not statistically significant.

Inpatients or patients with high-stage disease had a higher risk of developing a DVT. According to our results, the relative risk (RR) of DVT in an inpatient with carcinoma is 1.6 (p = 0.044); in a patient with high-stage disease, 2.2 (p = 0.001); and in a patient on treatment, 1.1 (not significant: p = 0.292).

Table 5 shows the logistic regression analysis results for PE (chi-square value of 36.3, df =6, p = 0.001, n = 397, -2 log likelihood value = 78). The data in this table show that inpatients with a carcinoma were more likely to have a PE than outpatients (p = 0.004, OR = 22.5). Those with high-stage disease were significantly more likely to have a PE than those with low-stage disease (p = 0.017, OR = 5.8). Patient age was also associated with a risk of PE (p = 0.002, OR = 1). Receiving treatment was associated with an increased risk of PE; however, this finding did not reach statistical significance. Patient sex was not associated with an increased risk of PE; this finding is not statistically significant.

Inpatients and patients with high-stage disease had a higher risk of developing a PE. According to our results, the RR of having a PE in an inpatient with carcinoma is 2.1 (p = 0.001); in a patient with high-stage disease, 1.8 (p = 0.019); and in a patient on treatment, 1.2 (not significant: p = 0.56).

We further analyzed all the data to assess the overall risk of venous thromboembolism--that is, DVT, PE, or both ( Table 6 ).

Table 6 shows the logistic regression analysis results for overall venous thromboembolism (chi-square value = 31, df =6, p = 0.001, n = 397, -2 log likelihood value = 149). The data in this table show that inpatients with a carcinoma were more likely to have a venous thromboembolism than outpatients (p = 0.023, OR = 2.8). Those with high-stage disease were significantly more likely to have a venous thromboembolism than those with low-stage disease (p = 0.001, OR = 5.6). Age was also associated with a risk of venous thromboembolism (p = 0.005, OR = 1). Receiving treatment was associated with an increased risk of venous thromboembolism; however, this finding did not reach statistical significance. Patient sex was not associated with an increased risk of venous thromboembolism; this finding is not statistically significant.

Therefore, inpatients and patients with high-stage disease have a higher risk of developing a venous thromboembolism.

According to our results, the RR of venous thromboembolism in an inpatient with carcinoma is 1.4 (p = 0.047); in a patient with high-stage disease, 2 (p = 0.001); and in a patient on treatment, 1.2 (not significant: p = 0.52).

At 6-month follow-up, four patients presented with clinically suspected symptomatic PE; three of these initally had an unsuspected PE and DVT, and one had an unsuspected DVT on staging CT. All returned within 1-2 months of staging CT. Findings on CT pulmonary angiograms were positive in two of the three patients. The recurrent PEs were larger than the initial PE and had more central filling defect on CT pulmonary angiography at the time of the symptomatic PE than at staging CT of unsuspected PE. The third person had negative findings on CT pulmonary angiography, and a Greenfield filter was placed on the basis of the staging CT findings of a DVT and a PE that was now symptomatic. The fourth person with an asymptomatic DVT (no asymptomatic PE) at staging CT had a clinically symptomatic PE. Because there was a strong clinical suspicion for PE in the presence of a known DVT, a Greenfield filter was placed.

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