Viscoelastic Testing for Assessment of Hypercoagulability and Thrombotic Risk in Cancer Patients: A Systematic Review

Background: Viscoelastic assays characterize haemostatic abnormalities in cancer, but their clinical prognostic value remains uncertain. We reviewed thromboelastography (TEG), rapid TEG and rotational thromboelastometry (ROTEM) for laboratory phenotyping and thrombotic risk assessment. Methods: PubMed/MEDLINE, Embase, Scopus and Web of Science Core Collection were searched through 15 October 2026. During revision, a second reviewer independently verified full-text decisions and extracted data and available quality assessments. Findings were synthesized by temporality, thrombotic endpoint, clinical setting and viscoelastic domain. The protocol was not prospectively registered. Results: The review included 64 reports published between 1997 and 2026: 38 grouped with clinical thrombotic endpoints and 26 primarily addressing laboratory findings. Forty-five reports used TEG and 19 used ROTEM. Laboratory abnormalities frequently involved faster clot propagation and increased clot strength, but normal or inconsistent profiles were also reported. Associations with existing thrombosis were distinguished from testing before incident events. High discrimination estimates sometimes belonged to multivariable models, while other studies found little independent prognostic information from TEG/ROTEM. Evidence for fibrinolysis-based prediction was limited and assay-dependent. Conclusions: Evidence supports laboratory haemostatic characterization more strongly than individual thrombosis prediction. Current findings do not establish that viscoelastic-guided thromboprophylaxis improves patient outcomes.