In a cohort study analysis reported in the Journal of Clinical Oncology, Valenza et al found that extended endocrine therapy after 5 years of adjuvant luteinizing hormone–releasing hormone agonist (LHRHa) treatment was associated with benefit among premenopausal women with node-positive, hormone receptor–positive breast cancer.
Study Details
The study involved data from two prospective cohorts—the Young Women’s Breast Cancer Study and IEO Breast Cancer Cohort. Eligible patients were diagnosed with early breast cancer at age ≤ 40 years between 2005 and 2016, had node-positive, hormone receptor–positive disease, and remained premenopausal after 5 years of adjuvant LHRHa with no evidence of recurrence. The primary outcome measure was invasive breast cancer–free survival, calculated from the sixth year after the initiation of adjuvant endocrine therapy, adjusted by propensity score weighting analysis.
Key Findings
Among 501 patients included in the analysis, 287 received extended endocrine therapy for a median of 3.7 years (interquartile range = 2.3–5.0 years); 48% received tamoxifen monotherapy and 52% received LHRHa plus tamoxifen or an aromatase inhibitor.
After a median follow-up of 7.3 years, propensity score weighted invasive breast cancer–free survival rates at 5 years were 85% in the extended endocrine therapy group vs 78% in the non–extended endocrine therapy group (hazard ratio [HR] = 0.63, 95% confidence interval [CI] = 0.44–0.89, P = .0135).
Propensity score weighted distant recurrence–free survival rates at 5 years were 91% in the extended endocrine therapy group vs 83% in the non–extended endocrine therapy group (HR = 0.49, 95% CI = 0.31–0.79).
In both groups, bone fractures and major cardiovascular events were reported in 1% of patients.
The investigators concluded: “In this cohort study analysis, extending [endocrine therapy] in premenopausal patients with node-positive [early breast cancer] after 5 years of LHRHa treatment was associated with a clinically meaningful reduction in both invasive and distant breast cancer recurrences.”
Ann H. Partridge, MD, MPH, of the Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, is the corresponding author for the Journal of Clinical Oncology article.
DISCLOSURE: The study was supported by the Breast Cancer Research Foundation and Susan G. Komen. For full disclosures of the study authors, visit ascopubs.org.
