American Board of Internal Medicine (ABIM) Certification Practice Exam

Before surgery, how long should tamoxifen be withheld?

1. 1 week

2. 2 weeks

3. 3 weeks

4. No withholding necessary

The correct answer is: 2 weeks

Withholding tamoxifen for two weeks prior to surgery is recommended to reduce the risk of potential complications related to thromboembolic events, particularly deep vein thrombosis (DVT) and pulmonary embolism (PE). Tamoxifen is a selective estrogen receptor modulator commonly used in breast cancer treatment, where it can increase the risk of these complications, especially in patients undergoing surgical procedures that may require prolonged immobility or are otherwise associated with a higher risk of thrombosis. In the context of surgery, allowing for a two-week period without tamoxifen prior to the procedure provides enough time for the drug's effects on coagulation factors to diminish, thus lowering the chances of postoperative thrombosis. This duration strikes a balance, ensuring the patient’s cancer treatment is not excessively interrupted while still prioritizing their surgical safety. Withholding tamoxifen for shorter periods, such as one week, may not provide adequate mitigation of the risk, while withholding it for three weeks or more could unnecessarily delay systemic management of breast cancer. The option of not withholding tamoxifen at all is generally not advised due to the heightened risk of thromboembolic complications associated with its use in the surgical context.