Guideline on Biomarkers for Metastatic Breast Cancer Therapy May Aid Treament Decisions

Biomarkers have been a game-changer in helping oncologists and their medical teams select appropriate treatments, and a new guideline can provide detailed information about whether systemic therapy will benefit patients with metastatic breast cancer.

Released in July 2015, the American Society of Clinical Oncology (ASCO) provided recommendations on the appropriate use of breast tumor biomarker assay results to guide decisions on systemic therapy for metastatic breast cancer.¹

ASCO convened a panel of experts to develop clinical practice guideline recommendations based on a systematic review of relevant medical literature. The panel developed its recommendations based on evidence found on MEDLINE and the Cochrane Library (from January 2006 through September 2014, to overlap with the search end date for the 2007 guideline update on tumor markers in breast cancer) as well as the clinical experience of panel members.

The guideline “provides evidence-based guidance on ordering biomarker tests for this patient population,” Catherine Van Poznak, MD, of the University of Michigan Health System and co-chair of the metastatic breast cancer guideline told OncoTherapy Network. “The document outlines the use of biopsy materials from metastatic foci, and provides direction on the use of results from assays of predictive and/or prognostic breast tumor biomarkers. The guideline addresses which biomarkers have sufficient evidence to be used to guide decisions on systemic therapy for women with metastatic breast cancer.”

Key recommendations:¹

• The panel recommended that biomarkers be used to assess newly diagnosed breast cancer patients with accessible metastases, by using biopsy for confirmation of disease process and testing of estrogen receptor (ER), progesterone receptor (PR), and HER2 status. The panel consensus is to preferentially use the ER, PR, and HER2 status from the metastasis to direct therapy, taking into consideration patient preference as well.
• Carcinoembryonic antigen (CEA), cancer antigen 15-3, and cancer antigen 27-29 may be used as adjunctive assessments--but not alone--to contribute to decisions regarding therapy, according to the guideline. Recommendations for tumor rebiopsy and use of circulating tumor markers are based on clinical experience and panel informal consensus in the absence of studies designed to evaluate the clinical usefulness of the markers. Because of this, clinicians may opt not to use these markers as adjunctive assessments.
• In patients already receiving systemic therapy for metastatic breast cancer, decisions on changing to a new drug or discontinuing treatment should be based on clinical evaluation, judgment of disease progression or response, and the patient's goals for care. There is no evidence at this time that changing therapy based solely on biomarker results beyond ER, PR, and HER2 improves health outcomes, quality of life, or cost effectiveness.

In the era of evidence-based medicine, it is important to note that making a change midstream may not necessarily benefit the patient; this depends on the status of the patient, the goals of the patient and the medical team, and the current available data on the information at hand. These are not always straightforward clinical decisions.

References:

• Van Poznak C, Somerfield MR, Bast RC, et al. (2015). Use of Biomarkers to Guide Decisions on Systemic Therapy for Women With Metastatic Breast Cancer: American Society of Clinical Oncology Clinical Practice Guideline. Journal of Clinical Oncology, Aug 20;33(24):2695-704.