A 46-year-old female presents with irregular menstrual bleeding that has persisted recently. Her medical history consists of 2 full-term pregnancies and invasive ductal carcinoma of the breast that was successfully treated with tamoxifen. She was recently diagnosed with type 1 endometrioid adenocarcinoma. Which of the following factors most likely increased this patient’s risk for developing this cancer?

  • A. Family history of breast cancer.
  • B. Oral contraceptive use.
  • C. Her pre-premenopausal stat.
  • D. multiple pregnancies.
  • E. Tamoxifen used to treat breast cancer.

Check your answer …

E: Tamoxifen.


Tamoxifen has a stimulatory effect on the endometrium, leading to an increased risk of developingendometrial hyperplasia and eventually endometrial carcinoma.

Tamoxifen is a selective estrogen receptor modulator (SERM) used in the treatment of estrogenreceptor positive breast cancer.

Tamoxifen is an estrogen agonist in endometrial tissue but an estrogen antagonist in thebreast. Therefore, while tamoxifen antagonist activity in the breast makes it an effective agent in thetreatment breast cancer, its agonist effect in the endometrial tissue of the uterus can lead toexcessive endometrial stimulation.

A benefit of the estrogenic activity of tamoxifen in bone is an increase in bone mineral density, makingtamoxifen a useful agent in the treatment of osteoporosis.