A cancer tissue biopsy does not always represent a patient’s entire tumor, thereby creating a bias towards certain treatments.
Tumor composition, especially of metastatic sites, can be probed by next-generation sequencing cell-free DNA (cfDNA) released by the tumor into the circulation. Testing cfDNA can be used to assess treatment effectiveness without an invasive procedure.
Ben Ho Park, MD, PhD, and colleagues assessed the concordance of pathogenic variants (genetic mutations associated with cancer) detected in tissue samples and cfDNA from 300 metastatic breast cancer patients.
They found a high concordance between cfDNA and tissue when samples were collected within a week apart. Concordance decreased with longer intervals between tissue and cfDNA testing. Some patients had variants detected in cfDNA but not tissue, highlighting the clinical utility of cfDNA for treatment decisions.
These findings, reported in JCO Precision Oncology, demonstrate that cfDNA is a reliable metric of tumor genomics, and can be used to monitor molecular changes in metastatic breast cancer longitudinally.
