Causal relationships between risk of venous thromboembolism and 18 cancers: a bidirectional Mendelian randomisation analysis.

1) There is strong observational evidence that active cancer is associated with venous thromboembolism.2) It is currently unknown whether venous thromboembolism is a risk factor for cancer.3) We applied a bi-directional Mendelian randomisation framework to appraise the causal relationships between genetically-proxied risk of venous thromboembolism and 18 different cancers.4) Overall, there was no clear evidence from Mendelian randomisation that lifetime-elevated risk of venous thromboembolism is causally associated with an increased risk of cancer, or visa versa.