Reviewing Key Genomic Assays in Breast Cancer

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A number of assays are available for testing breast cancer tissue, including Oncotype DX, MammaPrint, and Prosigna, David J. Dabbs, MD, states. Each of these tests has undergone various validation methodologies and can be conducted using formalin-fixed paraffin embedded (FFPE) blocks. To date, both the Prosigna and the Mammaprint tests are FDA approved for use with FFPE biopsies.

Prosigna is designed as a prognostic indicator of distant recurrence-free survival in postmenopausal women with HR-positive stage I/II breast cancer. Oncotype DX is intended for newly diagnosed patients with ER-positive, HER2-negative invasive breast cancer. The MammaPrint test can be utilized for most patients with early-stage breast cancer, regardless of HR and HER2 status.

Each of these tests are classified as in vitro diagnostic multivariate index assays (IVDMIA), defined as a combination of multiple variables that are interpreted using an algorithmic function. These tests are complex, with results that are difficult to translate for patients, requiring proper administration by pathologists, Dabbs notes. These assays are subject to FDA regulation, which helps to ensure accuracy.

Many of these molecular tests provide online ordering systems, local laboratory options, and the ability to review test results online. These tests can be ordered relatively simply, Dabbs suggests.