MKI67 and ductal breast carcinoma in situ: To assess the safety of the omission of RT in the low-risk DCIS, the ROMANCE randomized trial [22] integrated CPFs (age 50 years or older, margins ≥ 2 mm, size ≤ 2.5 cm, nuclear grade 1–2, and no necrosis) with biomolecular Luminal A-like features (positive hormonal receptors, HER2 negative, low Ki-67).