Concordance of genomic alterations by next generation sequencing (NGS) in tumor tissue vs. cell-free DNA in advanced breast cancer.

Abstract

11528Background: Cell-free DNA (cfDNA) is a non-invasive method of assessing mutations in the blood. This study compared the concordance between cfDNA and tissue biopsies across DNA genomic alterations in patients with advanced breast cancer (ABC). Methods: Forty-five patients with ABC who had both NGS testing with cfDNA (Guardant) and tissue DNA (Foundation One) for clinical management were included. 45-67 genes were common to both assays depending on when the assays were performed. Concordance was defined as the presence or absence of the identical genomic sequencing alteration(s) in a single gene. Results: Median time between assays was 3.3 months [range, 0-67 months]. Including all alterations and variants of unknown significance, the average number per patient for tissue and cfDNA was 4.50 (SD 2.96) and 1.98 (SD 2.13), respectively. Concordance between the two assays was 91.2%. Among only genes with reported genomic alterations in either assay (N=232), concordance was 10.3%. 15.0% of alterations foun...