Genomic Assays Impact Treatment Decisions in Patients With ER+ Breast Cancer

Matthew P. Goetz, MD, consultant, Division of Medical Oncology, Department of Oncology, Mayo Clinic, discusses how genomic assays can help identify patients with estrogen receptor (ER)—positive breast cancer who will benefit from the addition of chemotherapy to endocrine therapy.

There are a number of considerations when selecting a genomic assay for these patients, says Goetz. For the past 10 to 15 years, the focus has been on identifying patients with ER-positive disease who could do well with endocrine therapy alone versus those who need the addition of chemotherapy to treatment. A number of genomic assays are now in development to help identify those patients that can be de-escalated from chemotherapy.

Over the last few years, a number of different clinical trials have helped in identifying which genomic assays are most useful in this setting, and recent data have confirmed the utility of these assays in patient selection. Data suggest that the most useful assay is the Oncotype DX test, which assigns patients a recurrence score.