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William J. Gradishar, MD, FACP, FASCO
William J. Gradishar, MD, FACP, FASCO
Posted: Thursday, July 7, 2022
Given recent trial results for adjuvant CDK4/6 inhibitors in treating breast cancer, Meredith M. Regan, FASCO, ScD, of Dana-Farber Cancer Institute, Boston, and colleagues decided to reanalyze the results of the BIG 1-98, SOFT, and TEXT trials to estimate early relative and absolute treatment effects of an aromatase inhibitor versus tamoxifen, with ovarian suppression if patients were premenopausal, in clinical high-risk subgroups. More than 500 patients with hormone receptor–positive/HER2-negative disease and additional high-risk characteristics (≥ four positive lymph nodes or one to three positive lymph nodes with grade 3, primary tumor ≥ 5 cm, and/or Ki67 index ≥ 20%) participated in each trial. The team presented its findings at the 2022 American Society of Clinical Oncology (ASCO) Annual Meeting (Abstract 508).
The reanalysis revealed that in these high-risk subgroups, 5 years of aromatase inhibitor therapy versus tamoxifen therapy had a similar magnitude of early treatment effects after 2 to 3 years of follow-up for all patients versus treatment effects observed after a median follow-up in the monarchE trial of 27 months (hazard ratio = 0.70; Kaplan-Meier differences at 2 years, 2.7%; at 3 years, 5.4%; n = 5,637). Specifically, of the 695, 707, and 526 high-risk patients in the BIG 1-98, TEXT, and SOFT trials, 202, 122, and 142 disease-free survival events were observed, respectively, with 5 years of postrandomization.
“Relative and absolute treatment effects sometimes diminished when estimated over 5 years rather than over 2 years, but meaningful absolute differences remained at 5 years in contrast to the Penelope-B trial results,” noted Dr. Regan and co-investigators. “Design and interpretation of high-risk [hormone receptor–]positive/HER2-negative early breast cancer trials may depend on the timing of randomization and selection of backbone adjuvant treatments…, [and] follow-up [of more than] 5 years must remain standard.”
Disclosure: For full disclosures of the study authors, visit coi.asco.org.
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