ASCO Updated Guideline of Biomarkers in Metastatic Breast Cancer Supports PIK3CA, BRCA1/2, PD-L1 Testing

ASCO issued a new practice guideline update on the use of biomarkers in the management of metastatic breast cancer that revisits recommendations from the 2015 guideline and addresses topics that have emerged since then in the move toward personalized medicine in metastatic breast cancer. After reviewing relevant clinical trials published from 2015 to 2022, the expert panel found the strongest support for widespread testing for PIK3CA somatic variants, germline BRCA1/2 mutations, and PD-L1 expression. The updated guideline makes a total of 11 recommendations, including in cases in which the panel found insufficient evidence to recommend routine testing for specific biomarkers.