Resumption of Menses with Initiation of Letrozole After Five Years of Amenorrhea on Tamoxifen: Caution Needed When Using Tamoxifen Followed by Aromatase Inhibitors

Abstract

Background: Randomized trials in postmenopausal women have shown a benefit to substituting aromatase inhibitors for tamoxifen or using them sequentially following a full course of tamoxifen. The aromatase inhibitor letrozole has also been utilized for ovarian induction in premenopausal women. Case Report: A premenopausal woman with early stage breast cancer became amenorrheic with adjuvant chemotherapy, and remained so during 5 years of daily tamoxifen. After discontinuing tamoxifen, laboratory studies confirmed an apparent postmenopausal state. Menses resumed following a 2-week course of letrozole. Conclusion: Aromatase inhibitors need to be used with caution in women who stop menstruating following adjuvant chemotherapy or tamoxifen.

Keywords:

• Letrozole
• Tamoxifen
• Menses
• Aramatase Inhibitors.