Venous thromboembolism (VTE) contributes to morbidity and mortality although it is a treatable and even potentially preventable medical condition. The clinical manifestations of VTE vary from asymptomatic deep venous thrombosis (DVT) to potentially fatal pulmonary embolism (PE). Cancer is the main risk factor for VTE, and the incidence of cancer-associated thrombosis has increased during the last decade. VTE causes distress to cancer patients, interrupts and often delays anticancer therapy and increases morbidity, as well as general healthcare costs.

The association between cancer and venous thrombosis has been known for over a century. However, it is unclear how malignancy affects the hemostatic system and if VTE events could be predicted. It is challenging to know who will gain from preventative treatment of VTE and who will suffer from complications of anticoagulant therapy. Therefore, it would be valuable to identify potential clinical markers to predict VTE. If cancer patients with a considerable VTE risk were better recognized, individual thromboprophylactic approaches would be easier to design.

This study was designed to investigate the real-world incidence of VTE in a large hospital cohort and to evaluate, whether clinical and laboratory variables used in routine clinical care could predict VTE in cancer patients, especially in those with pancreatic cancer (PC) or high-grade serous ovarian cancer (HGSOC). We utilized the ability of a Finnish biobank to combine internationally unique real-world clinical data from different electronic health records. The overall aim was to find factors that could be used in clinical decision-making for VTE risk assessment among cancer patients.

In our study, about a quarter (26.9%) of patients with VTE had a concurrent cancer diagnosis. The highest VTE risk was associated with pancreatic, lung and ovarian cancer. During chemotherapy, VTE risk was increased among patients on platinum-based chemotherapy and those with elevated neutrophil counts. In patients with PC, short doubling time of the tumor marker CA 19-9 (CA 19-9-DT) significantly predicted VTE risk. Among patients with HGSOC, higher tumor marker CA 12-5 was associated with the risk of VTE, as well as a poor response to platinum-based cancer treatment.