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ASCO Breast Cancer Guideline Update on Use of 70-Gene Test

By: Meg Barbor, MPH
Posted: Monday, August 21, 2017

A focused update to the ASCO Breast Cancer Guideline delivers new recommendations on the use of the MammaPrint genomic test. The update, published in the Journal of Clinical Oncology, is intended to guide decisions on adjuvant systemic therapy for women with early-stage invasive breast cancer. It was initiated following the publication of the phase III randomized MINDACT study, which evaluated the MammaPrint 70-gene assay in 6,693 women with early-stage breast cancer.

Due to its ability to identify a good-prognosis population with potentially limited chemotherapy benefit, the MammaPrint assay may be used to inform decisions on withholding adjuvant systemic chemotherapy in women with estrogen receptor–positive or progesterone receptor–positive, HER2-negative, node-negative breast cancer, and HER2-negative breast cancer with one to three positive lymph nodes, who are at a high clinical risk of recurrence. According to the guideline, women meeting these criteria whose MammaPrint score is low may be treated with hormone therapy alone.

“Certain women with a low-risk score on MammaPrint may not need chemotherapy and may be spared its side effects,” said Ian Krop, MD, PhD, a medical oncologist at Dana-Farber Cancer Institute and Co-Chair of the expert panel that developed the guideline update. “However, this test is not suitable for all women with early breast cancer. For example, we do not recommend it for women with HER2-positive tumors or those with triple-negative breast tumors.”