When Cancer Clots: An Extensive Radiologic Analysis of Cancer-Associated Thromboembolism

Cancer-associated thrombosis (CAT) is a leading cause of morbidity and mortality in patients with malignancy, yet its imaging manifestations extend far beyond the conventional diagnosis of deep vein thrombosis and pulmonary embolism. This comprehensive review examines the full spectrum of CAT as encountered by radiologists, from routine venous thromboembolism to unusual-site thromboses, arterial thromboembolic events, catheter-related complications, and endovascular management strategies. Patients with cancer face a four- to seven-fold increased risk of venous thromboembolism compared with the general population, and arterial thromboembolism occurs at more than twice the expected rate, particularly within the first six months following cancer diagnosis. The radiologist's role spans detection, characterization, and therapeutic guidance across multiple vascular territories. Key diagnostic challenges addressed include the distinction between bland and tumor thrombus-a determination with direct implications for TNM staging, surgical planning, and systemic therapy selection-and the recognition of incidental thromboembolism, which carries prognostic weight equivalent to symptomatic events and warrants similar clinical management. Emerging applications of diffusion-weighted MRI, contrast-enhanced ultrasound, and FDG-PET/CT provide a multiparametric toolkit for thrombus characterization, while artificial intelligence and machine learning show promise for improving patient selection and reducing unnecessary imaging. The expanding recognition of cancer-associated arterial disease, including cerebrovascular, coronary, and peripheral arterial events, requires that cardiovascular structures receive systematic attention on routine oncologic imaging. Interventional radiology contributes actively to CAT management through inferior vena cava filtration, catheter-directed thrombolysis, and thrombolytic-sparing mechanical thrombectomy, the latter being particularly relevant in oncology patients with elevated bleeding risk. Conclusions: Realizing the full potential of imaging in CAT requires not only technical proficiency with individual modalities but a synthesized, oncology-informed interpretive approach that incorporates the patient's treatment history, biomarker status, and thrombotic risk profile at the time of image interpretation, positioning the radiologist as a central rather than peripheral figure in oncologic care.