Antithrombin Activity and Association with Risk of Thrombosis and Mortality in Patients with Cancer

Venous and arterial thromboembolism (VTE/ATE) are common complications in cancer patients. Antithrombin deficiency is a risk factor for thrombosis in the general population, but its connection to risk of cancer-associated thrombosis is unclear. We investigated the association of antithrombin activity levels with risk of cancer-associated VTE/ATE and all-cause mortality in an observational cohort study including patients with cancer, the Vienna Cancer and Thrombosis Study. In total, 1127 patients were included (45% female, median age: 62 years). Amongst these subjects, 110 (9.7%) patients were diagnosed with VTE, 32 (2.8%) with ATE, and 563 (49.9%) died. Antithrombin was not associated with a risk of VTE (subdistribution hazard ratio (SHR): 1.00 per 1% increase in antithrombin level; 95% CI: 0.99-1.01) or ATE (SHR: 1.00; 95% CI: 0.98-1.03). However, antithrombin showed a u-shaped association with the risk of all-cause death, i.e., patients with very low but also very high levels had poorer overall survival. In the subgroup of patients with brain tumors, higher antithrombin levels were associated with ATE risk (SHR: 1.02 per 1% increase; 95% CI: 1.00-1.04) and mortality (HR: 1.01 per 1% increase; 95% CI: 1.00-1.02). Both high and low antithrombin activity was associated with the risk of death. However, no association with cancer-associated VTE and ATE across all cancer types was found, with the exception of in brain tumors.

Automated summary

Venous and arterial thromboembolism are common complications in cancer patients. The connection between antithrombin deficiency and cancer-associated thrombosis is unclear. This study investigated the association of antithrombin activity levels with the risk of cancer-associated thrombosis and all-cause mortality in cancer patients. Antithrombin showed a U-shaped association with the risk of all-cause death, with both low and high levels associated with poorer overall survival. In patients with brain tumors, higher antithrombin levels were associated with the risk of thrombosis and mortality. However, no association was found between antithrombin and cancer-associated thrombosis in all cancer types, except for brain tumors.