Abstract Number: PB1110
Meeting: ISTH 2021 Congress
Background: Endocrine treatments with aromatase inhibitors (AI) or tamoxifen reduce the mortality of estrogen-positive breast cancer. While tamoxifen increases the risk of venous thromboembolism (VTE), whether AI influence hemostasis and the risk of VTE remains unclear. This information is critical when assessing women with breast cancer at high risk of VTE.
Aims: Among women with breast cancer, to evaluate the associations of AI or tamoxifen with changes on thrombin generation and sensitivity to thrombomodulin (TM).
Methods: We included 107 women with localized breast cancer, ≥4 weeks after breast surgery. Exclusion criteria were a planned chemotherapy, a personal history of VTE and a recent use of exogenous hormones. We measured the laboratory hemostatic profile before and 10-16 weeks after initiation of AI or tamoxifen. Thrombin generation (calibrated automated thrombography) was determined in platelet-poor plasma using 5 pM of tissue factor, 4 µM of phospholipids, and with/without 2 nM of TM. Variables of thrombin generation and of endogenous thrombin potential-based normalized TM sensitivity ratios (nTMsr) were compared using paired T-tests. All women provided informed consent.
Results: Compared with women using AI (n=65), women using tamoxifen (n=42) were younger (49.5y (SD=8.9) vs. 65.5y (SD=9.4)). Previous cardiovascular disease was rare (1.9%). Most common breast cancer stages were IA (51.4%), IIA (19.6%) and IIB (10.3%). Compared with baseline, the ETP and thrombin peak height were increased with tamoxifen therapy (+174nMxmin, 95%CI 34-142 and +33nM, 95%C I 21-44) but not with AI (+46nMxmin, 95%CI -4 to 95 and +8nM, 95%CI -2 to 17). NTMsr were increased with tamoxifen (+0.26, 95%CI 0.19-.033) but not with AI (+0.03, 95%CI -0.02 to 0.08).
Conclusions: Tamoxifen is associated with an in vitro hypercoagulable state that is not found in users of AI. This analysis provides some evidence supporting the use of AI in women with breast cancer at high risk of VTE.
To cite this abstract in AMA style:Blondon M, Thouvenin L, Lecompte T, Righini M, Fontana P, Bodmer A, Casini A. Differential Associations of Aromatase Inhibitors and Tamoxifen with Thrombin Generation and Sensitivity to Thrombomodulin: A Prospective Cohort Study [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 1). https://abstracts.isth.org/abstract/differential-associations-of-aromatase-inhibitors-and-tamoxifen-with-thrombin-generation-and-sensitivity-to-thrombomodulin-a-prospective-cohort-study/. Accessed September 24, 2021.
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