Some Breast Cancer Patients Can Safely Forgo Adjuvant Chemotherapy

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Certain patients with hormone receptor-positive, HER2-negative breast cancer do not benefit from the addition of chemotherapy to adjuvant endocrine therapy, according to results from the phase 3 RxPONDER trial published in the New England Journal of Medicine.

Postmenopausal patients who had 1-3 positive axillary lymph nodes and a recurrence score of 0-25 did not see improvements in invasive disease-free survival (iDFS) or distant relapse-free survival (dRFS) when chemotherapy was added to endocrine therapy.

In contrast, premenopausal patients with the same characteristics had significant benefits in iDFS and dRFS when they received both chemotherapy and endocrine therapy vs endocrine therapy alone.


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The RxPONDER trial (ClinicalTrials.gov Identifier: NCT01272037) included 5018 evaluable women with hormone receptor-positive, HER2-negative breast cancer who had 1-3 positive axillary lymph nodes and a recurrence score of 25 or lower.

Patients were randomly assigned to receive endocrine therapy alone (2507 patients) or chemotherapy plus endocrine therapy (2511 patients). In the overall cohort, the median age was 57.5 years (range, 18.3-87.6 years), and 66.8% of patients were postmenopausal (n=3353).

Results

In the overall patient population, there was no significant difference in iDFS between the treatment arms. The 5-years iDFS rate was 91.0% in the endocrine arm and 92.2% in the chemotherapy arm (hazard ratio [HR], 0.86; 95% CI, 0.72-1.03; P =.10).

Likewise, among postmenopausal patients, there was no significant difference in iDFS between the treatment arms. The 5-year iDFS rate was 91.9% in the endocrine arm and 91.3% in the chemotherapy arm (HR, 1.02; 95% CI, 0.82-1.26; P =.89).

However, among premenopausal patients, the 5-year iDFS rate was 89.0% in the endocrine arm and 93.9% in the chemotherapy arm, which translated to a significant benefit with chemotherapy (HR, 0.60; 95% CI, 0.43-0.83; P =.002).

For dRFS, there was no significant difference between the treatment arms in the overall cohort or among postmenopausal patients. The 5-year dRFS rate was 93.9% in the endocrine arm and 94.9% in the chemotherapy arm for the overall population (HR, 0.88; 95% CI, 0.71-1.09; P =.25). Among postmenopausal patients, the 5-year dRFS rate was 94.4% in both arms (HR, 1.05; 95% CI, 0.81-1.37; P =.70).

Among premenopausal patients, the 5-year dRFS rate was significantly higher in the chemotherapy arm than in the endocrine arm — 96.1% and 92.8%, respectively (HR, 0.58; 95% CI, 0.39-0.87; P =.009).

The relative benefit of chemotherapy observed in premenopausal patients did not increase with an increase in recurrence score, the researchers noted.

“We confirmed the prognostic value of a recurrence score between 0 and 25 in both premenopausal and postmenopausal participants with N1 breast cancer,” the researchers wrote. “[H]owever, the hypothesis that the relative chemotherapy benefit increases as the recurrence score value increases was not supported in either population.”

Disclosures: This research was supported by Genomic Health, the National Cancer Institute, the Susan G. Komen for the Cure Research Program, the Hope Foundation for Cancer Research, and the Breast Cancer Research Foundation. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

Reference

Kalinsky K, Barlow WE, Gralow JR, et al. 21-gene assay to inform chemotherapy benefit in node-positive breast cancer. N Eng J Med. Published online December 1, 2021. doi:10.1056/NEJMoa2108873



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