Expression of p53 Protein and Ki-67 in Atypical Ductal Hyperplasia, Ductal Carcinoma in Situ, and Microinvasive Ductal Carcinoma of the Breast

ABSTRACT

Mutation of the p53 gene is one of the most common genetic alterations in invasive breast carcinoma. However, it is unclear that the mutation usually occurs in noninvasive breast lesions. It might be expected that there is a correlation between histologic progression of breast lesions and proliferative rate. We investigated the expression of p53 protein and Ki-67 labelling index (LI) using immunohistochemistry in 16 ductal carcinoma in situ with microinvasion (DCIS-Mi), 56 DCIS, 15 atypical ductal hyperplasia (ADH), and 7 intraductal hyperplasia (IDH). Expression of p53 protein was detected in 33.9% of DCIS and 56.3% of DCIS-Mi and was confined exclusively in Van Nuys DCIS group 2 and 3. In ADH and IDH, no expression of p53 protein was found. There was no significant correlation between Van Nuys DCIS groups and Ki-67 LI. In conclusion, p53 mutation may be involved in the neoplastic progression from ADH to DCIS and is directly related to high nuclear grade and associated necrosis of DCIS.