However, HER-2 expression level appeared to be slightly higher in the metastatic sites than in the primary sites for this patient, which is consistent with the known results that HER-2 could be positively expressed in lymphatic metastasis lesions and distant metastasis lesions, while the primary tumors were HER-2 negative.[17,18] It was proposed that the balance of polyclone in a tumor may break and lead to a particular clone of high metastatic potential,[19] which may tend to migrate to different sites. This evidence concerns the gene ERBB2 and neoplasm.