Is Estradiol Monitoring Necessary in Women Receiving Ovarian Suppression for Breast Cancer?

The Oncology Grand Rounds series is designed to place original reports published in the Journal into clinical context. A case presentation is followed by a description of diagnostic and management challenges, a review of the relevant literature, and a summary of the authors' suggested management approaches. The goal of this series is to help readers better understand how to apply the results of key studies, including those published in Journal of Clinical Oncology, to patients seen in their own clinical practice.A 36-year-old premenopausal woman had been diagnosed with stage III breast cancer. After an initial biopsy confirmed breast cancer, she underwent mastectomy and axillary node dissection for a left-sided breast cancer, measuring 7 cm. The tumor had lobular histology and was considered grade 2 of 3. Metastatic carcinoma was identified in 10 of 13 axillary nodes. Immunohistochemical studies showed that the tumor was strongly positive for estrogen and progesterone receptor expression and had a Ki-67 score of 15% (> 20% is considered high according to a Swedish quality control study and the St Gallen Expert Consensus).(1,2) There was no amplification of the HER2/neu gene. Staging scans were negative for metastatic disease. In the adjuvant setting, she received three cycles of anthracycline-cyclophosphamide combination chemotherapy followed by three cycles of taxane chemotherapy and then locoregional radiotherapy. After completion of chemotherapy, she developed amenorrhea. As adjuvant endocrine therapy, she began monthly goserelin administration to achieve ovarian function suppression (OFS), in combination with the aromatase inhibitor (AI) exemestane. She experienced menopausal symptoms including hot flashes, vaginal dryness, and sexual dysfunction. After two monthly treatments with goserelin and exemestane, a sensitive assay for serum estradiol was checked and returned at 16 pg/mL (61 pmol/L); postmenopausal range for sensitive assay is less than 15 pg/mL (< 50 pmol/L). The patient has now been referred to our unit to discuss further management.