Use of Anticoagulants of Patients with Cancer-Associated Thrombosis Beyond 6 Months ; The Uscat Study, a 432-Patient Retrospective Non-Interventional Study

Introduction

Few data are available about the treatment and complications beyond 6 months and up to 12 months in Cancer-associated Thrombosis (CAT) patients initially treated with low-molecular-weight (LMWH). Study objectives were to document the prescription and use of the anticoagulant treatment beyond 6 months and up to 12 months in CAT patients initially treated with tinzaparin and to measure clinical outcomes.

Methods

Adult CAT patients with solid tumor, previously included in 2 prospective cohort studies (AXA - NCT02898051; PREDICARE - NCT03099031) and still alive at the end of the initial 6-month treatment period with tinzaparin were eligible to participate in this retrospective non-interventional French multicenter study.

Main study outcome was the description of the anticoagulant treatment in the management of CAT patients in usual medical care from the 6^th month to the 12^th month.

Secondary objectives included the incidence of VTE recurrence, bleeding and deaths. A sample size of 250 to 300 patients was considered appropriate to allow analyses of 6-to-12-month data post-index event based on descriptive statistics.

Results

A total of 432 patients aged 66.5±12.7 years of whom 52.1% female alive at the end of AXA and PREDICARE 6-month treatment period were included in this retrospective study; 332 patients were followed up to 12 months while 96 patients deceased before the end of the study and 4 patients were lost-to-follow-up.

Most patients (91.9%) had a single-site cancer. Cancers were mostly solid tumors and primary sites were colorectal (21.6%), lung (20.1%) or breast (16.8%); a proportion of 82.1% of patients had stage III or IV malignancy while cancer was progressing in 51.2% of patients.

Beyond 6 months, the anticoagulant treatment was maintained in 290 of 421 (68.9%) patients of whom 241 (83.1% [95% CI: 78.3%; 87.2%]) patients were treated with a LMWH and 233 (80.3%) with tinzaparin, 32 (11.0%) and 13 (4.5%) patients were treated with vitamin K antagonists (VKA) and direct oral anticoagulants (DOAC), respectively. The anticoagulant treatment was discontinued in 131 of 421 (31.1%) patients of whom 63 patients had already stopped the anticoagulant before 6 months while 68 patients stopped the anticoagulant treatment at 6 months. Mean treatment duration with LMWH beyond 6 months was 121.6 ± 65.6 days representing a mean total treatment duration of 288.4 ± 85.0 days since the index event.

Between 6 and 12 months, 24 (5.7%) patients experienced a VTE recurrence corresponding to a cumulative incidence of 8% [95% CI: 4.2%; 15.1%], while 11 (2.7%) patients had a major bleeding corresponding to a cumulative incidence of 2.6% [95% CI: 1.3%; 5.1%]. VTE recurrence was more frequent in patients with colorectal and lung cancer while major bleeding was more frequent in patients with colorectal cancer (Table) A total of 96 (22.3%) deaths corresponding to a cumulative incidence of 30.7% [95% CI: 22.3%; 30.7%] were reported of which 55 (12.8%) related to cancer, 1 (0.2%) to bleeding and 8 (1.9%) to another cause while the cause of death was not documented for 32 (7.5%) patients. Clinical outcomes according the type of cancer are summarized in the Table.

Conclusion

These results reporting the clinical course up to 12 months of a large cohort of patients still alive at the end of the initial 6-month period following the VTE index event, provide data contributing to the clinician's therapeutic decision when facing a patient completing 6 months of anticoagulant for a CAT. Site of cancer has to be taken into account when assessing the risk of subsequent VTE recurrence and bleeding.

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