Venous thromboembolism

Treatment with tamoxifen is commonly considered an independent risk factor for venous thromboembolism.91,92 Data from multiple trials and systematic reviews suggest that the use of tamoxifen for chemoprevention in otherwise healthy women increases the risk of thromboses two- to threefold.93–96 This translates to an absolute risk of two to three cases per 1,000 people per year.93,94Venous thromboembolism can be associated with significant morbidity and mortality, with up to 15% 3-month mortality rates in those with pulmonary embolism and up to 70% post-thrombotic syndrome rates for lower extremity deep venous thromboembolism.97–99 Furthermore, multiple population-based studies have demonstrated that the risk of thromboembolism increases exponentially with age. The risk for those younger than 20 years is one in 100,000, for those 40–75 years old is one in 1,000, and for those older than 75 years is 1 in 100.100–102 Overall, the age-adjusted annual incidence rate for venous thromboembolism is higher in men (130/100,000) compared to that in women (110/100,000), except during the childbearing years, when the incidence in women is higher.102–104After age 45, incidence rates are generally higher in males.103 Men on average are diagnosed with breast cancer a decade later than women, so their baseline risk of thromboembolism at the time they start hormonal treatments is higher than that of their female counterparts due to both age and sex. Furthermore, there has been at least one case report of venous thromboembolism as the presenting sign of male breast cancer.105 Based on numerous clinical trials and studies in women that demonstrate that tamoxifen is an independent risk factor for venous thromboembolism, we extrapolate that men on tamoxifen are also likely at increased risk for thrombosis and their potential sequelae. Therefore, a careful personal history assessing for risk factors for thromboses and a family history evaluating for thrombophilia should be performed in all men prior to initiation of hormonal therapy. More studies are needed looking at the potentially deadly risk of blood clots in men on hormonal treatment for breast cancer.

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Male breast cancer survivors are a special population. There are no randomized clinical trial data in male breast cancer patients to guide treatment and follow-up recommendations, so we extrapolate from guidelines developed for women with breast cancer and for men with other cancers to outline reasonable follow-up care for male breast cancer survivors. Men are at risk of many of the same treatment-related sequelae as women, and they may suffer a great psychosocial burden from their diagnosis. More research is needed to help tailor therapeutic choices and to increase support for men with breast cancer.


This publication was made possible by Clinical and Translational Science Award grant numbers UL1 TR000135 and KL2TR000136-09 from the National Center for Advancing Translational Sciences, a component of the National Institutes of Health. Its contents are solely the responsibility of the authors and do not necessarily represent the official view of National Institutes of Health.


The authors report no conflicts of interest in this work.

Raina M Ferzoco, Kathryn J Ruddy

Department of Oncology, Mayo Clinic, Rochester, MN, USA 


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