Venous thromboembolism and risk stratification in hematological malignancies

Patients with hematologic malignancy have an increased risk of venous thromboembolism (VTE) compared to the general population. This risk is highest during the first months after diagnosis and subsequently decreases over time. The risk of VTE in leukemia ranges from less than 1% to almost 7% within the first 6-months of diagnosis, and is higher in patients with acute leukemia compared to chronic leukemia. The risk of VTE in lymphoma ranges from less than 1% to almost 20% in the first year of diagnosis, varying by lymphoma type. Risk is lowest in patients with indolent lymphoma and highest in those with aggressive lymphoma, including central nervous system (CNS) lymphoma. The risk of VTE in multiple myeloma is highest in the first 6-months of diagnosis and decreases over time. Despite incorporation of thromboprophylaxis strategies in many patients, 6-month incidence of VTE remains greater than 10%. Primary thromboprophylaxis has the potential to decrease risk of VTE in patients at high-risk. Clinical risk prediction models can quantify risk of VTE, thereby identifying those at high-risk. VTE risk prediction models are available for patients with leukemia, lymphoma and multiple myeloma. However, these models either require external validation or have room for improvement in VTE risk discrimination. Future efforts should focus in validation of available models, incorporation of biomarkers as predictors of VTE, and evaluation of the risk/benefit of thromboprophylaxis in high risk patients.