In a randomised trial, primary prophylaxis in high-risk patients with lung or gastro-intestinal cancers lowered incidence of thromboembolism.

Based on results from randomised trials, current guidelines recommend primary prophylaxis against venous thromboembolism (VTE) for high-risk outpatients with cancer (J Clin Oncol 2023; 41: 3063-3071). However, few ambulatory patients with cancer receive VTE prophylaxis. Australian investigators identified 200 high-risk outpatients – defined as those with either elevated fibrinogen or D-dimer levels – who were being treated for gastrointestinal (GI) or lung cancer and randomised them to receive either low-molecular-weight heparin (LMWH) VTE prophylaxis or no prophylaxis. In addition, 128 low-risk patients (without elevation of fibrinogen or D-dimer) were followed in a low-risk observational arm.

In the randomised comparison between LMWH and no LMWH among high-risk patients, the LMWH group had significantly fewer thromboembolic events (8% vs 23%; number needed to treat, seven) and significantly lower six-month mortality (13% vs 26%; NNT, six). In the low-risk observational cohort, thromboembolism occurred in 8% of patients, and six-month mortality was 7%. Bleeding was uncommon (less than 2%) and not different among groups. 

Comment: This study adds to the evidence showing that high-risk outpatients with lung or GI cancer – when appropriately risk stratified – can benefit substantially from pharmacological VTE prophylaxis. Risk stratification in this trial was done with D-dimer and fibrinogen levels, but other validated tools also are available (e.g. the Khorana Risk Score). Despite lack of blinding, this study should persuade physicians to provide VTE prophylaxis to high-risk outpatients with cancer; direct-acting oral anticoagulants are an acceptable alternative to LMWH. In an accompanying editorial, Dr Khorana (who developed the aforementioned risk score) calls for systematic efforts to improve access to prophylaxis in suitable patients.

Daniel D. Dressler, MD, MSc, MHM, FACP, Professor of Medicine, Emory University School of Medicine, Atlanta, USA.

Alexander M, et al. Risk-directed ambulatory thromboprophylaxis in lung and gastrointestinal cancers: the TARGET-TP randomized clinical trial. JAMA Oncol 2023; 9: 1536-1545.

Khorana AA. Primary thromboprophylaxis in people with cancer – where next? JAMA Oncol 2023; 9: 1545-1546.

This summary is taken from the following Journal Watch titles: General Medicine, Oncology and Hematology, Ambulatory Medicine.