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Effect of tamoxifen on venous thrombosis risk factors in women without cancer: the Breast Cancer Prevention Trial
Author(s) -
Cushman Mary,
Costantino Joseph P.,
Bovill Edwin G.,
Wickerham D. Lawrence,
Buckley Lenore,
Roberts John D.,
Krag David N.
Publication year - 2003
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1046/j.1365-2141.2003.03976.x
Subject(s) - tamoxifen , antithrombin , medicine , breast cancer , placebo , venous thrombosis , protein c , cancer , protein s , oncology , gastroenterology , thrombosis , heparin , pathology , alternative medicine
Summary. Tamoxifen reduces breast cancer incidence among healthy women, but is associated with an increased risk of venous thrombosis. We studied the 6 month effects of tamoxifen on venous thrombosis risk factors in women without cancer. One hundred and eleven women at one centre who were participants in a multicentre breast cancer prevention trial were randomized, in double‐blind fashion, to receive 20 mg/d of tamoxifen or placebo. The activated protein C (APC) ratio and concentrations of antithrombin, protein C antigen, and total protein S were measured at baseline and 6 months of treatment. None of the factors changed over 6 months in placebo‐treated women. Among tamoxifen‐treated women, antithrombin and protein S, but not protein C or APC ratio were reduced. Sequential antithrombin concentrations with tamoxifen were 114% and 104% ( P = 0·001 compared with placebo). Sequential protein S concentrations with tamoxifen were 18·42 and 17·30 µg/ml ( P = 0·02 compared with placebo). Reductions in antithrombin and protein S were greater in postmenopausal women, but did not differ by other risk factors for venous thrombosis, such as body mass index. Reductions of antithrombin and protein S, but not protein C or APC resistance, might relate to the increased risk of venous thrombosis associated with tamoxifen treatment.