Reasons Influencing Long-Term Anticoagulant Treatment Beyond 6 Months for Cancer-Associated Thrombosis in USCAT, A 432-Patient Retrospective Non-Interventional Study.

Background and objectives: Few data are available about anticoagulation management beyond 6 months in patients with cancer associated thrombosis (CAT). Our objective was to describe anticoagulant treatment modalities up to 12 months. Methods: The management of the anticoagulant treatment beyond 6 months was described in this initially retrospective non-interventional French multicenter study in patients treated with low-molecular-weight heparins (LMWH) still alive at the end of an initial 6-month treatment period. Clinical outcomes, including venous thromboembolism, recurrence, bleeding and deaths have been published previously. Results: Among the 432 patients (mean age 66.5±12.7 years) included in the study, 332 were followed up to 12 months while 96 patients deceased before study end and 4 patients were lost-to-follow-up. At 6 months, anticoagulant therapy was stopped in 74 patients, 56 were switched to vitamin K antagonists (VKA) (16.1% [95%CI, 12.4%-20.4]), 30 to direct oral anticoagulants (DOAC) (8.6% [95%CI, 5.9%-12.1]). LMWHs were maintained in 256 patients (73.6% [95%CI, 68.6-78.1]). During the follow-up, LMWHs were definitively discontinued in 86 patients (33.7%), the main reason being a favorable course of the cancer (16 patients, 18.6%), or the thromboembolic disease (11 patients, 12.8%), whereas concern about bleeding risk was low (2 patients, 2.3%). Conclusion: Anticoagulation beyond 6 months and up to 12 months was in accordance with clinical practice guidelines suggesting that treatment should be continued as long cancer is active or in the absence of bleeding risk. Anticoagulant treatment discontinuation beyond 6 months was influenced by the favorable courses of both malignancy and thromboembolic disease, as well as patient's preference.