ERBB2 and ductal breast carcinoma in situ: However, the risk stratification of all four clinical trials [3, 4, 9, 10] based merely on histological grade is criticized by Toss et al. [7], who emphasize that trial outcomes will be influenced by the inherent subjectivity of the current simple grading system and that DCIS risk stratification should be a combination of histologic grading and more objective biomarkers such as ER and HER2 [7], molecular markers, or deep learning strategies on digital images.