The primary objective of the trial was to determine the pharmacodynamic effects of a 4-week course of lapatinib administered preoperatively to patients with HER2-positive DCIS measuring protein expression of phospho extracellular-regulated kinase (pERK), phosphor-AKT (pAkt) and proliferative/apoptosis markers at baseline and post treatment. This evidence concerns the gene ERBB2 and ductal breast carcinoma in situ.