Predicting recurrent venous thromboembolism in cancer: is it possible?

The association between cancer and venous thromboembolism (VTE) is well-established. Many clinical and laboratory risk factors of a first cancer-associated VTE have been identified. In contrast, the pathogenesis of recurrent VTE in cancer patients is less well studied. There is only very limited information on the importance of clinical risk factors and the role of biomarkers in this context has never been studied. Patients with cancer-associated VTE usually receive low-molecular-weight heparin for at least 3 to 6 months. Nevertheless, the recurrence risk during anticoagulation is as high as 10% and treatment-related major bleeding is more common in cancer-patient than in non-cancer patients. Thus improvement of current treatment concepts is warranted. One important step to achieve this task is developing strategies that allow distinguishing patients with a high risk of recurrent VTE (who may benefit from prolonged or even intensified anticoagulation) from those with a low risk (i.e. patients in whom a shorter period of anticoagulant treatment at lower dose may be sufficient). Recently, a risk assessment model (RAM) for predicting recurrent VTE has been presented. By combining 4 clinical patient characteristics (sex, cancer type and stage, history of VTE), the Ottawa score allows stratification of cancer patients according to their VTE recurrence risk. The prediction tool was successfully validated in more than 800 patients from 2 prospective VTE treatment studies. Before this RAM can be introduced into routine clinical practice, however, management studies and impact analyses are required.