The American Society of Clinical Oncology has issued updated guidelines on using breast tumor biomarker assays to help guide or influence decisions on systemic therapy in women with metastatic breast cancer, which were published online July 20 in the Journal of Clinical Oncology.
The quality of evidence for the recommendations ranges from insufficient to intermediate, and the “strength” of the recommendation was moderate for all of them.
When evaluating metastatic sites, it is important to note that the estrogen receptor (ER), progesterone receptor (PR), and/or human epidermal growth factor receptor 2 (HER2) status may have changed from the primary tumor, and these results could influence treatment. Thus, biopsy should be offered to patients with accessible, newly diagnosed metastases from primary breast cancer, to confirm disease status and test for ER, PR, and HER2 status, wrote Dr. Catherine Van Poznak of the University of Michigan Comprehensive Cancer Center in Ann Arbor, and colleagues, as one of the key recommendations (J. Clin. Oncol. 2015 July 20 [doi:10.1200/JCO.2015.61.1459]).
Patients should be also be told if discordances are detected, and that evidence is lacking to determine whether outcomes are better with treatment regimens based on receptor status in the metastases or the primary tumor.
If supported by the clinical scenario and patient goals for care, the ASCO Panel consensus is to preferentially use the biomarker status from the metastatic site rather than from the primary tumor, to direct therapy.
Decisions for initiating systemic therapy in this patient population should be based on clinical evaluation, judgment, as well as patient preferences. At present, there is no evidence that health outcomes will improve if treatment is initiated based solely on the results of biomarker assays that go beyond ER, PR, and HER2 status.
For patients who are already receiving systemic therapy, decisions for changing drugs or regimens, or discontinuing treatment should be based on clinical evaluation, clinician judgment of disease progression or response, and patient preference and input. 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, they wrote. This recommendation applies for both tissue biomarkers and circulating tumor biomarkers.
The guidelines also recommend that carcinoembryonic antigen, cancer antigen 15-3, and cancer antigen 27-29 can be used as adjunctive assessments and can contribute to decisions regarding therapy. The data thus far, however, are insufficient to recommend their use alone for monitoring response to treatment. This recommendation, according to the researchers, is based on clinical experience and the informal consensus of the panel, since there are no studies that have been designed to evaluate the clinical utility of the markers.
It is also reasonable for clinicians to not use these markers as adjunctive assessments.
Outside of clinical trials, decisions for systemic therapy should be influenced by ER, PR, and HER2 status, as the clinical usefulness for other biomarkers has not yet been demonstrated. A number of other types of biomarkers are in active development, but there is insufficient evidence at this time showing that their use improves cancer outcomes, the panel said.
Biomarker distribution of ER, PR, and HER2 status may also differ across ethnic and racial backgrounds, and in addition to the biologic variability of these biomarkers, there is also evidence that disparities exist in the frequency of biomarker testing in certain populations.