PO35 | A MULTICENTRE AUDIT OF CURRENT TUMOUR THROMBOSIS MANAGEMENT IN THE UNITED KINGDOM

A.A. Bhatti¹, L. Tafesh¹, A. Waton¹, M. Thomas³, N. Prasannan³, A. Bhide³, R. Walsh³, T. Lucas³, K. White⁴, T. Bariana⁴, O. Tsiamita⁴, S. Soman⁴, P. Woolley⁵, I. Lacej⁵, K. Musgrave^1|2 | ¹Newcastle Upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK; ²Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK; ³University College London Hospitals NHS Foundation Trust, London, UK; ⁴Barts Health NHS Trust, London, UK; ⁵Imperial College Healthcare NHS Trust, London, UK

Background. Tumor thrombus is the extension of a tumor into the intravascular space; its management remains uncertain. This UK-wide audit examined current anticoagulation practice and patient outcomes.

Methods. A multicenter audit was conducted across four hospital trusts. Data were collected via review of electronic patient records. VTE events were defined as new bland thrombosis non-contiguous with the tumor. Progression of tumor thrombus was recorded separately. Outcomes were compared using Fisher’s exact test with significance set at p < 0.05.

Results. Between January 2023 and December 2024, 156 individuals were identified with a mean age of 62.6 years (range 2-99) and 55% male. The commonest primary cancer sites were hepatopancreatobiliary (32%), renal (18%) and gastrointestinal (12%). Metastatic disease was present in 109 (70%). Tumor thrombus most frequently involved the splanchnic veins (40%), pulmonary vasculature (24%), inferior vena cava (22%) and renal veins (17%). Radiological reports identified associated bland thrombosis in 27 patients (17%). At baseline, non-contiguous VTE was present in 14 patients (9%). Ninety patients (58%) received anticoagulation. 81 (52%) individuals were given therapeutic anticoagulation, 9 (6%) received prophylactic anticoagulation and 66 (42%) received no anticoagulation. Low-molecular-weight heparin was the most common anticoagulant, used in 72 (80%) of anticoagulated patients. Surgical thrombectomy was performed in 13 cases (8%). At six months, a new or recurrent VTE event occurred in 8 individuals (10%) receiving therapeutic anticoagulation, 1 (11%) receiving prophylactic anticoagulation and 2 (3%) without anticoagulation (p>0.05). Major or clinically relevant non-major bleeding was observed in 17 (21%), 1 (11%), and 7 (11%) patients, respectively (p > 0.05). Tumor thrombus progression occurred in 20 (25%) on therapeutic anticoagulation, none on prophylactic anticoagulation, and 10 (15%) without anticoagulation (p > 0.05). Overall six-month mortality 45% (70/156). Mortality differed significantly between groups: 31% (25/81) on therapeutic anticoagulation, 78% (7/9) on prophylactic anticoagulation and 58% (38/66) without anticoagulation (p<0.05).

Conclusions. Our results show no difference in VTE rate or bleeding events between different treatment approaches. Mortality rates were lower for individuals who received therapeutic anticoagulation, but these may have been a fitter population. Prospective clinical trials are needed.