乌鸦传媒

Women who have clinically high-risk, hormone receptor (HR)-positive, HER2-negative breast cancer may use results of the MammaPrint genomic assay to inform decisions about the need for adjuvant chemotherapy, according to a clinical guideline update.

Results of the assay can help inform decision-making for women with estrogen receptor (ER)-positive or progesterone receptor (PR)-positive. The test offers no guidance for women with clinically low-risk HR-positive disease, an expert panel concluded in a focused update to the American Society of Clinical Oncology to inform decision-making adjuvant systemic therapy for early invasive breast cancer.

"Some women with breast cancer are more likely to have a recurrence of cancer and need to receive chemotherapy to lower this risk," panel co-chair Vered Stearns, MD, of Johns Hopkins in Baltimore, said in a statement. "The MammaPrint test can now be added to the list of tests that help clinicians identify women who need chemotherapy and those who do not."

"Certain women with a low-risk score on MammaPrint may not need chemotherapy and may be spared its side effects," added panel co-chair Ian Krop, MD, PhD, of Dana-Farber Cancer Institute in Boston.

Published online in the and on the ASCO website, the focused update did not change the guideline's principal recommendation to limit routine biomarker testing to hormone-receptor and HER2 status. The guideline identified several other tests that might be considered in specific clinical situations, but the list did not include the MammaPrint.

The panel added MammaPrint for selected patients on the basis of the MINDACT trial, which was reported shortly after ASCO released the and was subsequently described in detail in the .

The trial involved 6,700 women, including 3,380 patients with clinically high-risk disease. Among 1,550 women with clinically/pathologically high-risk disease but low-risk by MammaPrint criteria, the 5-year distant metastasis-free survival did not differ significantly between women who had chemotherapy and those who did not.

Investigators estimated that use of MammaPrint results to inform decision-making was associated with a 42% reduction in the use of chemotherapy, with no increase in the risk of breast cancer mortality or metastatic disease.

"Women in the low clinical risk category did not benefit from chemotherapy, regardless of genomic MammaPrint risk group," the expert panel noted. "Therefore, the MammaPrint assay does not have clinical utility in such patients. If a patient has hormone receptor-positive, HER2-negative, node-positive breast cancer, the MammaPrint assay may be used in patients with one to three positive nodes and a high clinical risk to inform decisions on withholding adjuvant systemic chemotherapy."

With regard to determining clinical risk, the panel suggested the criteria published by (website currently unavailable but included in the data supplement of the guideline).

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