Mandatory tumor and serum samples were collected ( N = 808 ; 58 % to 99.8 % were assessable ) , and amphiregulin , betacellulin , epidermal growth factor ( EGF ) , transforming growth factor alpha , EGF receptor , HER2 , HER3 , insulin-like growth factor 1 receptor , PTEN , phosphorylated AKT , PIK3CA , CMYC , serum HER2 extracellular domain ( sHER2 ) , and FCR were assessed using appropriate assays .