American Board of Internal Medicine (ABIM) Certification Practice Exam

What is a potential risk associated with tamoxifen in women over age 55?

1. Breast cancer recurrence

2. Endometrial cancer

3. Osteoporosis

4. Cardiac events

The correct answer is: Endometrial cancer

Tamoxifen is a selective estrogen receptor modulator primarily used in the treatment and prevention of breast cancer. While it is effective in reducing the risk of breast cancer recurrence, particularly in women who have already been diagnosed with hormone receptor-positive tumors, it is also associated with an increased risk of developing endometrial cancer, especially in postmenopausal women over the age of 55. The mechanism behind this increased risk involves tamoxifen’s estrogenic effects on the endometrium. In women over age 55, who are generally postmenopausal, the exposure to tamoxifen can lead to abnormal proliferation of the endometrial lining, potentially leading to hyperplasia and subsequently increasing the likelihood of endometrial cancer. This risk must be taken into consideration when weighing the benefits and risks of tamoxifen therapy in older women, especially those with certain risk factors for endometrial cancer. In contrast, although tamoxifen may have some impact on bone density, its primary role is not to promote osteoporosis; instead, it can have a protective effect on bone health in postmenopausal women. At the same time, cardiac events related to tamoxifen are generally less pronounced compared to its benefits for breast cancer treatment. Lastly, while