Molecular Test Predicts Breast Cancer Prognosis

A molecular assay is available that identifies intrinsic subtypes of breast cancer from histological specimens so that the samples are handled within routine clinical practice.

The assay is a quantitative reverse transcription polymerase chain reaction (RT-qPCR) used on samples from fresh-frozen and formalin-fixed, paraffin-embedded tissues.

The PAM50 Breast Cancer Intrinsic Classifier measures the expression of 50 classifier genes and 5 control genes to identify the intrinsic subtypes known as Luminal A, Luminal B, human epidermal growth factor receptor (HER2) enriched and Basal-like. Together with a categorical classification of breast cancer subtype, the assay also provides quantitative values for proliferation, luminal gene expression, estrogen receptor -1 gene (ESR1), progesterone receptor gene (PGR) and human epidermal growth factor receptor 2 gene (ERBB2 or HER2/neu).

The PAM50 test offered by ARUP Laboratories, (Salt Lake City, UT, USA), is the first clinical iteration of this gene expression signature, which has already been extensively validated in the research setting. Standard methods for diagnosing and treating breast cancer include anatomic staging, histological assessment, and molecular testing for specific gene expression. The development of the PAM50 signature was the culmination of a decade of work that became a multiinstitutional project.

Philip Bernard, MD, medical director at ARUP, said, "Although many gene sets have been used as surrogates for biologic subtyping of breast cancer, the PAM50 has proven to be a more accurate predictor of patient outcome than standard methods. Having additional information about the tumor biology and quantitative data on biomarkers already used for treatment decisions is the first step towards personalized health care in oncology."

The PAM50 is the beginning of a suite of multianalyte gene expression oncology tests offered by ARUP Laboratories and is complemented by other mutation tests that are already available.

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