ESR1 and ductal breast carcinoma in situ: In one of the largest studies to date of multiple markers, Kerlikowske et al. (22), examining a 329 case cohort, identified different combinations of proteins to be predictive of recurrence as DCIS (ER-/HER2+/Ki67+ or COX2−/Ki67+/p16+) or IBC (COX2+/Ki67+/p16+).