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Genetic and Rare Diseases Information Center (GARD)

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Factor V Leiden thrombophilia


* Not a rare disease
Other Names for this Disease
  • APC resistance, Leiden type
  • Hereditary resistance to activated protein C
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Your Question

Wondering if there is a connection between factor V Leiden and breast cancer? I have read that many people with breast cancer have factor V Leiden, but wondering which came first? I have asked many people and no one seems to have the answer.

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

Is factor V Leiden and breast cancer related?

No. Factor V Leiden is the most common inherited form of thrombophilia. Between 3 and 8 percent of people with European ancestry carry one copy of the factor V Leiden mutation in each cell.[1] Factor V Leiden and breast cancer are not known to be causally related; however, due to the high prevalence of mutations, it is quite possible for women with breast cancer to also have a mutation in factor V Leiden. In addition, testing for factor V Leiden (and other common genetic risk factors for thrombophilic events) may be ordered for breast cancer patients to assess risks for blood clots and stroke. For example, a number of studies have been done assessing the rate of  tamoxifen-associated thrombophilic events in breast cancer patients with factor V Leiden mutations.[2]
Last updated: 8/22/2013