[What's new liquid biopsy-PIK3CA testing in breast cancer]

The impact of liquid biopsies on the analysis of molecular alterations of circulating tumor DNA (ctDNA) has recently increased. PIK3CA is one of the most frequently mutated genes in breast cancer and the expected approval of targeted PIK3CA therapy based on the results of the SOLAR1 trial is likely to lead to the use of liquid biopsies as another promising testing strategy in breast cancer patients who can benefit from a targeted therapy.Choosing an appropriate method for the detection of activating PIK3CA mutations should include factors like sensitivity, specificity, and limit of detection. The test should at least meet the parameters of the assay used in the drug approval study.If carefully used, PIK3CA mutation detection with liquid biopsies can then be a useful addition to standard tissue diagnostics.