Patients with cancer have an increased risk of Venous Thromboembolic Events (VTE), since cancer tissue and anticancer agents have thrombogenic effects, associated with hypercoagulability and vascular damage. Patients with cancer have 1,6% incidence of VTE in two years, complication associated with decreased survival. Due to that, some select ambulatory cancer patients benefit from primary thromboprophylaxis.

This review's objective is to inform the health professionals about the prophylaxis of thromboembolism in ambulatory patients with solid tumors.

Literature review. The databases used were PubMed, SciELO and Google Scholar. The terms used in the search were: “venous thromboembolism”, “solid tumor”, “prophylaxis”.

Primary thromboprophylaxis is recommended in hospitalized patients with cancer. In the case of ambulatory patients, the benefit of routine prophylaxis is unclear and depends highly on the clinical scenario, due to the risk involving anticoagulants. These drugs are associated with bleeding complications with the incidence of 0.7%‒14%. Therefore, patients with cancer have increased bleeding risk and the anticoagulation may increase this possibility. The selection of these patients can be made with the stratification of the risk of VTE. In ambulatory care, risk assessment can be conducted based on a validated risk assessment tool, Khorana score, which has been available for over a decade, and includes assessment of the site of cancer, hematologic parameters and body mass index. Advanced age, prior VTE and family history of VTE are also associated with an increased risk. With this classification, patients with cancer and an intermediate-to-high-risk of VTE have a recommendation of thromboprophylaxis. Direct Oral Anticoagulants (DOACs) are now the first choice for thromboprophylaxis, while Low Molecular Weight Heparin (LMWH) can be considered as an alternative for patients with drug interactions involving DOACs or with primary gastroesophageal cancer.

The role of anticoagulation for primary prevention of VTE in outpatients has been elucidated by new evidence from randomized trials. Emerging studies continue to optimize risk prediction approaches and may improve the identification of outpatients that may benefit from thromboprophylaxis. Patient education on cancer-associated thrombosis and its warning signs and symptoms is fundamental.