S100A7 and ductal breast carcinoma in situ: S100A7 encodes the protein psoriasin part of the S100 family containing calcium‐binding motifs and is an important cell mediator for, for example, cell survival and maturation and has been associated to tumor progression and survival.38 In a study by Liu et al, psoriasin was shown to promote invasion and survival of pancreatic cancer cells.39 Other studies have shown that psoriasin is more highly expressed in, for example, squamous skin cancer in situ compared to invasive squamous skin cancer,40 and in DCIS compared to invasive breast cancer,41, 42 which is in line with our findings.