CT imaging for occult malignancy in patients with unprovoked venous thromboembolism (VTE) in a tertiary centre: is it worthwhile?

Background: Investigating patients with unprovoked venous thromboembolism (uVTE) for occult malignancy can prove a diagnostic dilemma and imaging is often used extensively in this patient group.

Aims: The primary objective of this study was to determine the incidence of malignancy on CT and other imaging over a 10-year period. A secondary objective was to evaluate the role of laboratory and other non-imaging tests performed.

Methods: A retrospective key word search of our hospital's imaging system was performed to identify patients with unprovoked DVT/PE over the last 10 years. All imaging, histology, endoscopy, laboratory tests, and clinical follow-up over 2 years were analysed. Patients with provoked VTE were excluded.

Results: 150 patients had uVTE. 9 patients were diagnosed with occult malignancy by different investigations on index hospital admission (3 patients) or subsequently on clinical follow-up (6 patients). Mean age of patients was 62 years. 116 patients had CT body imaging. The incidence of malignancy diagnosed by initial CT imaging was 1.7% with a sensitivity of 22%, specificity 87%, and PPV 12.5%. Overall incidence of malignancy identified by imaging alone during the index hospital admission was 2%. Total incidence of malignancy including index admission and follow-up was 6%. Median time to cancer diagnosis was 12 months.

Conclusion: CT imaging had a low yield for diagnosing malignancy. Extensive imaging strategies increase cost and radiation exposure without improving mortality. Clinical follow-up, history taking, and physical examination guiding appropriate investigations remain the best tool for unmasking occult malignancy in patients with uVTE.