Good Outcome Reported With Endocrine Therapy and Omission of Chemotherapy Based on 21-Gene Recurrence Score in Breast Cancer
Treatment with adjuvant endocrine therapy and omission of chemotherapy on the basis of a 21-gene recurrence score ≤ 11 was associated with a high 3-year disease-free survival rate in women with hormone receptor–positive, HER2-negative breast cancer, according to a trial reported in the Journal of Clinical Oncology by Gluz et al of the West German Study Group.
Study Details
The trial evaluated adjuvant anthracycline-containing and anthracycline-free regimens in 3,198 patients with node-positive or high-risk node-negative HER2-negative early breast cancer. Recurrence score results were available for 2,568 local-laboratory hormone receptor–positive patients; of them, 18% were classified as low recurrence score (≤ 11); 60%, as intermediate recurrence score (12–25); and 22%, as high recurrence score (> 25).
Chemotherapy was omitted in 348 patients (15% of evaluable patients) on the basis of a recurrence score ≤ 11; among these patients, 31% had node-positive disease, and 20% had grade 3 disease.
Outcomes
After a median follow-up of 35 months, 3-year disease-free survival in patients with a recurrence score ≤ 11 and endocrine therapy alone was 98%, compared with 92% among those with a recurrence score > 25 and 98% among those with a recurrence score of 12 to 25 who received chemotherapy. Among all patients, nodal status, central and local laboratory grade, Ki67 protein, estrogen receptor status, progesterone receptor status, tumor size, and recurrence score were prognostic for disease-free survival on univariate analysis; on multivariate analysis, only nodal status, central and local laboratory grade, and recurrence score were significant factors.
The discordance rate for histologic grade between central and local laboratories was 44%. The recurrence score had moderate positive correlation with Ki67 protein and grade and moderate negative correlation with estrogen receptor and progesterone receptor status.
The investigators concluded: “In this prospective trial, patients with enhanced clinical risk and omitted chemotherapy on the basis of [recurrence score] ≤ 11 had excellent 3-year survival. The substantial discordance observed between traditional prognostic markers and [recurrence score] emphasizes the need for standardized assessment and supports the potential integration of standardized, well-validated genomic assays such as [recurrence score] with clinicopathologic prognostic factors for chemotherapy indication in early hormone receptor–positive [breast cancer].
The study was supported by Genomic Health, Sanofi Aventis, and Amgen.
Oleg Gluz, MD, of the West German Study Group, Evangelical Hospital Bethesda, Mönchengladbach, is the corresponding author of the Journal of Clinical Oncology article.
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