Posted: Wednesday, June 29, 2022
Etienne Brain, MD, PhD, of the Institute Curie, Saint-Cloud, France, and colleagues conducted a large phase III randomized trial called Unicancer ASTER 70s on the effect of adjuvant endocrine therapy plus chemotherapy in elderly women with estrogen receptor–positive, HER2-negative breast cancer who had a high tumor genomic grade index. Their findings, which were presented at the 2022 American Society of Clinical Oncology (ASCO) Annual Meeting (Abstract 500), reported no significant overall survival benefit with the addition of chemotherapy to endocrine therapy following surgery.
A total of 1,089 female patients aged 70 and older with estrogen receptor–positive, HER2-negative primary breast cancer or isolated local relapse were included in this phase III trial. Charlson comorbidity index and 4-year mortality Lee scores were collected at baseline, and the tumor genomic grade index was determined by reverse transcription–polymerase chain reaction on formalin-fixed paraffin-embedded samples.
Patients with a high genomic grade index were randomly assigned at a 1:1 ratio to receive chemotherapy plus endocrine therapy versus endocrine therapy alone. Standard endocrine therapy consisted of 5 years of an aromatase inhibitor, tamoxifen, or a sequence based on patient tolerance. Investigators chose between three chemotherapy regimens, and the primary objective was to demonstrate an overall survival benefit for chemotherapy in the intent-to-treat population. Secondary objectives included breast cancer–specific survival, invasive disease–free survival, event-free survival, and quality of life.
Findings revealed 180 overall survival events with Charlson comorbidity index and Lee score at > 14, ≤ 2, and ≤ 8 in 60%, 62%, and 84% of patients, respectively. Tumors were ≥ pT2, pN+, isolated local relapses, with histologic grade 3, in 56%, 46%, 11%, and 39% of cases, respectively. Overall, there were no significant differences observed between the arms for overall survival (hazard ratio [HR] = 0.85 [0.64–1.13], P = .2538), and the 4-year overall survival was 90.5% with chemotherapy plus endocrine therapy and 89.7% with endocrine therapy alone.
Disclosure: For full disclosures of the study authors, visit coi.asco.org.