Several biomarkers are routinely used in clinical practice. For example, HER2 is a protein overexpressed in some breast cancers and guides the use of trastuzumab therapy. Similarly, KRAS mutations in colorectal cancer can predict non-response to certain anti-EGFR therapies. Other examples include BRCA1/BRCA2 mutations in breast and ovarian cancers, which can influence the decision to use PARP inhibitors.
