ERBB2 and breast cancer: The fact that 55-75% of patients with premalignant DCIS overexpress HER-2/neu in their tumor lesions and 75% of breast cancers are HER-2/neu negative would suggest the progression of HER-2/neu positive DCIS to HER-2/neu negative breast cancer is only in the tumor clones that express IFN-γ Rα.