Invited discussant Harold ­Burstein, MD, PhD, Associate Professor of Medicine at Harvard Medical School and a medical oncologist at Dana-Farber Cancer Institute and Brigham & Women’s Hospital, Boston, called MINDACT “a heroic effort” whose results show that combining stage, pathology, and genomic signature “is a powerful strategy for determining prognosis in estrogen receptor–positive breast cancer.”

The findings support those of other studies, most recently the West German Study Group phase III PlanB trial, which showed 3-year disease-free survival to be 97.9% in women with N1 disease and a low 21-gene recurrence score.¹ “Patients with up to three positive nodes and a very low genomic score did outstanding in this trial, even though they had node-positive disease,” Dr. Burstein noted.

The emerging concept, he said, is that integration of clinical and genomic information allows for tailored treatment of this subset of women “such that many can avoid chemotherapy.”

“I am struck that most women with estrogen receptor–positive, HER2-negative stages I and II cancers with up to three positive nodes warrant genomic profiling, so they can make the best possible choice about whether or not to receive chemotherapy,” he continued. In short, according to Dr. Burstein, it is time to “broaden the threshold” for selecting patients who might avoid chemotherapy.

Will MammaPrint give Oncotype DX a run for its money? Not according to Dr. Burstein, who pointed out that the 21-gene recurrence score currently offers “the most robust data” for predicting which patients do and do not need chemotherapy. The validation of MammaPrint in MINDACT does, however, “broaden the opportunity to use genomic signatures in node-positive patients to a degree we haven’t seen before,” he said.

An Issue Not Resolved

Moving forward, Dr. Burstein said more data are needed on discordance—especially for perplexing cases, such as genomically low-risk patients with HER2-positive tumors—and on the benefit of chemotherapy in the intermediate-risk group—an issue not resolved by MINDACT.

“The study didn’t really show that you can use this assay to determine who needs chemo or not for the intermediate-risk group,” he said. “Would a different assay take you out of that uncertainty box for the intermediate group? At the moment the answer is no.” ■

Disclosure: Dr. Burstein reported no potential conflicts of interest.

Reference

1. Gluz O, Nitz UA, Christgen M, et al: West German Study Group phase III PlanB trial: First prospective outcome data for the 21-gene recurrence score assay and concordance of prognostic markers by central and local pathology assessment. J Clin Oncol. February 29, 2016 (early release online).