ERBB2 and cancer: Next-generation sequencing was performed (Oncomine Precision Assay, Thermo Fisher Scientific, Waltham, MA) with cell-free tumor DNA (ccfDNA) obtained immediately before treatment, to assess the mutational status of a panel of 50 cancer-related genes, including HER2, HER3, HER4, TP53, PIK3CA, PTEN, EGFR, and AKT1.