In this study, patients with HER2-positive primary breast cancer (T1c-3 N0-1 M0; target lesion ≤ 7 cm) were randomized to different lengths of neoadjuvant induction anti-HER2 therapy with lapatinib and trastuzumab followed by weekly paclitaxel plus anti-HER2 therapy, and in estrogen receptor (ER)-positive patients, with or without endocrine therapy; the primary endpoint was comprehensive pCR (CpCR) rate, including residual ductal carcinoma in situ of the breast (ypT0 or Tis). The gene discussed is ESR1; the disease is ductal breast carcinoma in situ.