A retrospective observational study found an acceptable risk of recurrence (8.6%) and major bleeding (1.4%) during 3 months of follow-up in 70 cancer patients with recurrent VTE while on anticoagulant therapy who either switched from VKA therapy to LMWH (23 patients) or had their LMWH dose increased by If there is no reversible reason for recurrent VTE while on anticoagulant therapy, and anticoagulant intensity cannot be increased because of risk of bleeding, a vena caval lter can be inserted to prevent PE.172 However, it is not known if insertion of a lter in these circumstances is worthwhile, and the AT10 panel consider this an option of last resort. *29. In patients who have recurrent VTE on VKA therapy (in the therapeutic range) or on dabigatran, rivaroxaban, apixaban, or edoxaban (and are believed to be compliant), we suggest switching to treatment with LMWH at least temporarily (Grade 2C). Remarks: Recurrent VTE while on therapeutic-dose anticoagulant therapy is unusual and should prompt the following assessments: (1) reevaluation of whether there truly was a recurrent VTE; (2) evaluation of compliance with anticoagulant therapy; and (3) consideration of an underlying malignancy. A temporary switch to LMWH will usually be for at least 1 month. *30. In patients who have recurrent VTE on long- term LMWH (and are believed to be compliant), we suggest increasing the dose of LMWH by about one- quarter to one-third (Grade 2C). Remarks: Recurrent VTE while on therapeutic-dose anticoagulant therapy is unusual and should prompt the following assessments: (1) reevaluation of whether there truly was a recurrent VTE; (2) evaluation of compliance with anticoagulant therapy; and (3) consideration of an underlying malignancy. Conclusion There is substantial new evidence since AT9 about how to treat VTE. 