Cancer-associated venous thrombosis in adults (second edition): A British Society for Haematology Guideline

One in two people will develop cancer at some point in their lives¹ and venous thromboembolism (VTE) will complicate the clinical journey of one in 20 cancer patients.² Cancer confers a fourfold increase in the risk of VTE compared with patients without cancer³ and mortality is threefold higher in cancer patients with VTE than those with no VTE.⁴ The addition of thrombotic complications is an important cause of mortality, morbidity and emotional distress. Advancements in treatment options for those with primary and metastatic disease have resulted in patients living longer with increased access to systemic anti-cancer therapy (SACT). This has increased the number of patients at risk of cancer-associated thrombosis (CAT). Cancer also increases the risk of arterial thromboses, for example leading to stroke, but to a lesser extent than it does venous thromboses. In common with other guidelines and consensus statements on this topic, CAT in this manuscript refers to VTE and does not include arterial thromboses. The management of thrombosis in paediatric cancer is covered in a separate British Society for Haematology guideline.⁵

In the intervening years since the last British Society for Haematology (BSH) guideline on CAT,⁶ there have been a number of new randomised controlled trials (RCTs) and other types of clinical studies in this field. These studies have generated new data on the use of direct oral anticoagulants (DOACs) in both the treatment and prophylaxis of CAT. As a result, new or updated international guidelines or consensus statement have been produced to serve as broad a readership as possible, but by doing so rarely address the specific cultural and healthcare system nuances of different countries. This BSH guideline is written with a UK readership in mind, focusing on therapeutic options available in the National Health Service and readily accessible in the United Kingdom.

Clinical guidelines help guide decision-making by offering recommendations for healthcare professionals based on the best available evidence. However, the data that inform the recommendations are rarely representative of the entire CAT population since the studies typically excluded patients at risk of bleeding, with poor performance status, prognosis or abnormal renal and liver function. As such, guidelines are not a vade mecum of CAT management and should be applied in the context of each patient as an individual. The views of patients may vary according to their previous experiences of CAT and their current understanding of their condition. Where management decisions are not clear cut, good practice is to review realistic options with the patient and make a shared decision based on their personal preferences and values.