3, 4, 8, 9 and 13) were still proliferative lesions without progression to DCIS or IDC, although they acquired an additional PIK3CA (E726K) with or without a RUNX1 (P267fs) and another PIK3CA (H1047R) mutation, or a PIK3CA (E545K) mutation (Fig. 2a). Here, PIK3CA is linked to ductal breast carcinoma in situ.