OFS Therapy and E2 Levels in Young Women With Breast Cancer

By: Victoria Kuhr, MS
Posted: Monday, October 21, 2024

Ann H. Partridge, MD, MPH, of the Dana-Farber Cancer Institute, Boston, and colleagues observed that over half of patients receiving gonadotropin-releasing hormone (GnRH) agonist plus oral endocrine therapy for hormone receptor (HR)-positive breast cancer had at least one plasma estradiol (E2) level higher than 2.72 pg/mL during the first 4 years after diagnosis. These findings were published in npj Breast Cancer. Related factors at 1 year were no prior chemotherapy and tamoxifen use.

“Larger studies exploring the clinical implications of incomplete E2 suppression by GnRH agonists are needed to ensure optimal ovarian function suppression treatment strategies are being employed for this population,” the investigators commented.

The study included women with breast cancer younger than age 40 receiving GnRH agonist treatment plus oral endocrine therapy for early and de novo metastatic HR-positive breast cancer at 1 and 4 years after diagnosis. A total of 109 patients, 84 in the 1-year blood sample and 25 in the 4-year blood sample, were included in the study. Of them, 54.7% and 60% had E2 levels higher than 2.72 pg/mL at 1 year and 4 years after diagnosis, respectively. Factors associated with E2 levels higher than 2.72 pg/mL at 1 year were no prior chemotherapy (P = .045) and tamoxifen use (P = .009).

After a median follow-up of 7 years, among patients with stage I to III breast cancer (n = 74), invasive breast cancer–free survival events were seen in six patients (8.1%) with E2 levels higher than 2.72 pg/mL and five patients (6.8%) with E2 levels lower than 2.72 pg/mL (P = .893). Among patients with de novo metastatic breast cancer (n = 12), six patients (50%) with E2 levels higher than 2.72 pg/mL and three patients (25%) with E2 levels lower than 2.72 pg/mL died during follow-up (P = .052).

Disclosure: For full disclosures of the study authors, visit nature.com.

npj Breast Cancer