Importantly, correlations have been reported between high baseline shedding of Her2/neu ECD and poor response to trastuzumab, suggesting that the ECD may represent a useful serum marker as a prognostic indicator and as a predictor of response to treatment in breast cancer patients (Hoopmann et al, 2003; Bethune-Volters et al, 2004). Here, ERBB2 is linked to breast carcinoma.