Cancer patients undergo routine imaging studies much more than others. The widespread use of the recently introduced multi-detector CT scanners has resulted in an increasing number of incidentally diagnosed pulmonary embolism (PE) in asymptomatic cancer patients. The significance and clinical outcome of such incidental PE is described.

Both radiology department and hospital databases were searched for all cancer patients with a diagnosis of incidental PE. CT scans were performed using a 64-slice scanner with a 5.0 mm slice thickness.

During the study period, 34 patients with incidental PE were identified. The mean age (±SD) was 57.7 (±12.4) years. All patients had active cancer, gastric, lung, colorectal, and lymphomas being the most frequent. Most patients had advanced-stage disease at the time of PE diagnosis; 26 (77%) patients had stage IV, whereas only 3 patients had stages I or II disease. Twenty-seven (79%) patients had their PE while undergoing active treatment with chemotherapy (68%) or radiotherapy (12%); none, however, were on hormonal therapy. Most (74%) patients had their PE diagnosed without history of recent hospital admission. Except for 5 (15%), all other patients were anticoagulated. With follow-up, 2 patients developed recurrent PE, 2 others had clinical and echocardiographic evidence of pulmonary hypertension, and 9 (26%) died suddenly within 30 days of the diagnosis of incidental PE; 2 of these where among the 5 patients who were not anticoagulated.

Incidental PE in cancer patients is increasingly encountered. Similar to symptomatic PE, many were diagnosed in patients with advanced stage disease and while undergoing active anti-cancer therapy. A significant percentage of patients had recurrent emboli, pulmonary hypertension, and sudden death.