Some Older Women With Breast Cancer May Be Able To Avoid Chemotherapy, Study Finds

Certain older patients with estrogen receptor (ER)-positive, HER2-negative breast cancer may be able to skip chemotherapy treatment after undergoing endocrine therapy, according to final findings from the phase 3 Unicancer ASTER 70s study.

Researchers noted that this study was particularly important, because research often excludes older or more frail patients from trials.

“ASTER 70s is a landmark trial for older patients with breast cancer due to a few success factors … it broke the rule for the design using non-restrictive inclusion criteria, allowing some populations with potential frailty or local relapse,” study author Dr. Etienne Brain, of the Institut Curie in France, said while presenting the findings.

Read more: Clinical Trial Exclusions: Are Researchers Missing Out?

The findings, which were presented at the 2022 ASCO Annual Meeting, showed that women over the age of 70 with ER-positive, HER2-negative breast cancer with a high tumor genomic grade index (which uses a set of 97 genes to determine tumor grade) had no significant difference in overall survival (time from treatment until death of any cause) between those who had chemotherapy after endocrine therapy and those who did not.

Study participants with high tumor genomic grade index were randomly assigned to receive endocrine therapy then adjuvant chemotherapy or endocrine therapy alone. Patients with low genomic grade tumor index scores did not receive chemotherapy. The standard endocrine therapy administered was five years of an aromatase inhibitor, tamoxifen or a treatment based on what patients can tolerate.

The main goal of the study was to determine the percentage of patients in each group who were alive after four years. The researchers found that at the four-year mark, 89.4% of patients in the endocrine therapy alone group and 98.6% of patients in the endocrine therapy plus chemotherapy group were alive.

Of note, 11% of the study population overall did not take their medications as prescribed, though this number rose to 20.5% of patients in the chemotherapy group. There was also a higher rate of side effects for patients given chemotherapy.

When factoring in for chemotherapy non-adherence, researchers found that four-year overall survival rates were 91% and 89.3% for the chemotherapy and non-chemotherapy groups, respectively.

“Although protocol analysis suggested a potential benefit of chemotherapy, the message of caution is that these benefits remain marginal, and there is a minimization of selection bias in the role of randomization to control the distribution,” Brain explained.

Brain emphasized that when choosing a treatment regimen, patients and clinicians should work together and utilize genomic grade index — which could have prognostic value — as well as goals of treatment to determine the best plan.

“In older patients with breast cancer, the value of any prognostic signature would require actually factoring in specific geriatric data,” Brain said, “and a better selection of the right endpoint, which, in older (patients) should always combine quality of life and survival.”

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