The American Society of Clinical Oncology (ASCO) updated its guidelines to include the 70-gene MammaPrint assay to direct decisions for some patients with breast cancer.1

The updates are based on data gathered from the MINDACT trial ( Identifier: NCT00433589), which enrolled 6693 women with histologically determined operable invasive breast cancers, 0 to 3 positive nodes, and no distant metastases.

Clinical risk was determined by using the Adjuvant! Online clinical risk criteria, and genomic risk was determined by the MammaPrint assay.

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Patients with low clinical and genomic risk did not receive chemotherapy, patients with high clinical and genomic risk received chemotherapy, and patients with mismatched clinical and genomic risks were randomly assigned to receive chemotherapy or not.

Patients with high clinical risk and low genomic risk who received chemotherapy had a 5-year distant metastasis–free survival (DMFS) of 95.9% (95% CI, 94.0-97.2) vs 94.4% (95% CI, 92.3-95.9) in women who did not (hazard ratio, 0.78; 95% CI, 0.50-1.21; P = .27).

Genomic assays may assist clinicians in guiding decisions to withhold chemotherapy, decreasing the risk of exposing patients to the adverse effects of chemotherapy who would experience minimal benefit.

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The study authors recommended that if “…a patient has hormone receptor–positive, human epidermal growth factor receptor 2 (HER2)–negative, node-negative breast cancer, the MammaPrint assay may be used in those with high clinical risk to inform decisions on withholding adjuvant systemic chemotherapy…”


  1. Krop I, Ismaila N, Andre F, et al. Use of biomarkers to guide decisions on adjuvant systemic therapy for women with early-stage invasive breast cancer: American Society of Clinical Oncology clinical practice guideline focused update. J Clin Oncol. 2017 Jul 10. doi: 10.1200/JCO.2017.74.0472 [Epub ahead of print]