Should We Screen Oncotype DX Eligible Patients With Breast MRI?

Oncotype DX is a genomic test used to predict chemotherapy benefit and recurrence risk in early stage breast cancer patients. A previous study has shown that in patients with multiple tumors sent for Oncotype DX analysis, differing results between the tumors were yielded that ultimately changed chemotherapy management in 27% of cases. The purpose of this study is to determine the utility of preoperative MRI in Oncotype DX eligible patients.

A retrospective, Institutional review board approved study identified 888 consecutive new breast cancer patients from 2012 to 2016 at a single institution and identified 541 patients who potentially would be eligible for Oncotype DX. Frequency of additional disease in this population group was recorded. The method of imaging used, either conventional imaging (mammography and ultrasound) or additional MRI, was evaluated.

Of 541 patients, 360 patients had conventional imaging performed only and 181 patients had an additional breast MRI. Of 541 patients, 73 patients (13.5%) had additional biopsy proven multifocal, multicentric, or contralateral tumors identified. The total number of additional disease within the conventional imaging group was 39 of 360 patients (10.8%), vs 34 of 181 patients (18.8%) in the MRI group, which was statistically significant (P = 0.02). Total 34 of 73 patients (46.6%) had additional disease only detected by MRI.

In patients who may be eligible for Oncotype DX evaluation, 13.5% of patients were found to have additional disease. Nearly half of the patients had additional disease only detected by MRI, indicating the potentially utility of preoperative MRI in this patient population.