Incidental pulmonary emboli are associated with a very high probability of progressive malignant disease on staging CT scans.

Purpose: The link between malignancy and venous thromboembolism (VTE) is well established; the risk has been shown to be higher in certain tumour types and in patients receiving platinum-based chemotherapy regimens. 'Active' cancer is often quoted as being a particular risk factor for VTE, but the definition varies widely and the supporting evidence is weak. This study was conceived to establish whether incidental pulmonary emboli are associated with an increased likelihood of progressive disease on a staging computed tomography (CT) scan.

Materials And Methods: All CT scans containing incidental PEs over the course of a year in a large specialist cancer hospital were examined (n = 306). An age-matched control group was assembled. Multivariate logistic regression analysis was performed to establish the relationship of several independent variables, including progressive disease, with the dependent variable of the presence or absence of incidental pulmonary emboli.

Results: Progressive disease was present in 144 of 306 (47.1%) of the patients in the PE group but only 63 of 306 (20.6%) of the control group patients. Progressive disease on the staging CT scan was found to have an odds ratio for incidental PE of 3.46, with a 95% CI of 2.38-5.01. Receiving platinum-based chemotherapy resulted in an odds ratio of 3.89 (2.41-6.28) for PE. Receiving non-platinum-based systemic anti-cancer therapy (SACT) resulted in an odds ratio for PE of 1.71 (1.16-2.50).

Conclusion: The detection of an incidental PE on a staging CT scan is associated with a very high risk of progressive malignant disease.