ERBB2 and neoplasm: The biomarkers measured were HER2 (protein and mRNA), HER3 (protein and mRNA in tumor tissue), epidermal growth factor receptor (EGFR) (protein and mRNA in tumor tissue), amphiregulin (serum protein and mRNA), betacellulin (mRNA), IGF-1R (protein), PTEN (protein), transforming growth factor alpha (TGFα) (serum protein), epidermal growth factor (EGF) (serum protein), serum HER2/shed HER2 (sHER2), amplifications of c-Myc or topoisomerase 2A (TOP2A), and mutations in phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA).