Guideline Update on Use of Biomarkers for Adjuvant Endocrine and Chemotherapy in Breast Cancer

A panel of expert members of the American Society of Clinical Oncology used informal consensus to develop updated recommendations on the appropriate use of breast cancer biomarker assay results to guide decisions about using adjuvant endocrine and chemotherapy for early-stage breast cancer (J Clin Oncol. 2022; doi:10.1200/JCO.22.00069). These recommendations were based on evidence from 24 randomized clinical trials and prospective-retrospective studies published from 2016 to October 2021. The updates focused on women with breast cancer whose estrogen receptor (ER) and human-epidermal-growth-factor–receptor 2 (HER2) status is known. 

In the last few years, new data produced since the 2016 guideline was published have enabled experts to formulate additional guidance on the use of biomarker tests based on patient age and number of affected lymph nodes. As a result, the updated guidelines provide more precise guidance on how to use previously endorsed genomic tests. 

In addition, new biomarkers and new applications have been developed since the 2016 guidelines were issued. These innovations include biomarkers for programmed cell death receptor ligand-1 (PD-L1), tumor-infiltrating lymphocytes (TILs), and circulating tumor DNA (ctDNA) as well as the application of biomarker test results to guide decisions about the use of extended endocrine therapy. As a result, the updated guidelines provide recommendations on the use of these new biomarkers to guide decisions about treatment with endocrine therapy and chemotherapy in women with ER+, HER2− tumors and in those with HER2+ or triple-negative tumors.

“Treatment decisions should also consider disease stage, comorbidities, and patient preferences,” wrote Fabrice Andre, MD, Institute Gustave Roussy, Paris, France, and fellow members of the expert panel.

According to the updated guidelines, for patients who are postmenopausal or 50 years or older and have early-stage breast cancer that is ER+, HER2−, and node-negative or that includes 1 to 3 positive nodes, providers may use Oncotype DX, MammaPrint, the Breast Cancer Index (BCI), and EndoPredict to guide adjuvant endocrine therapy and chemotherapy. In postmenopausal patients with node-negative ER+ and HER2−, providers may use Prosigna and BCI. In postmenopausal patients without access to genomic tests, Ki67 may be used with other parameters or their immunohistochemistry 4 score to guide decisions on the use of adjuvant therapy. 

In premenopausal patients with node-negative ER+ and HER2− breast cancer, providers may use Oncotype. However, current data indicate that premenopausal patients with 1 to 3 positive nodes benefit from chemotherapy regardless of the results of genomic assays. For patients with 4 or more positive nodes, no data is available on the use of genomic tests to guide adjuvant chemotherapy.

In patients with 0 to 3 positive nodes who received 5 years of endocrine therapy and have no evidence of cancer recurrence, BCI may be used to guide decisions about extending endocrine therapy. However, for women with HER2+ or triple-negative breast cancer, none of the available assays are recommended for use in guiding treatment decisions.