Moreover, overexpression of HER2 has also been associatedwith the resistance to certain chemotherapeutics,6 risk of brain metastasis,7 andother types of cancers such as stomach, ovarian, and lung cancer.8 In blood, sHER2 can be detected in approximately45% of patients with HER2-related breast cancers.9 This evidence concerns the gene ERBB2 and breast cancer.