While HER2 showed over 93% concordance by both IHC and FISH between primary tumor and paired metastatic sites, in patients who had not received anti-HER2 drugs [79], the large study by Park et al., showed that 5.7% of metastases from initially HER2-negative tumors were HER2-positive, predominantly in liver metastases [80]. This evidence concerns the gene ERBB2 and neoplasm.