TP53 alterations in atypical ductal hyperplasia and ductal carcinoma in situ of the breast.

Abnormalities in the TP53 tumour suppressor gene in 75 atypical ductal hyperplasias and 62 ductalcarcinomas in situ (DCIS) of the breast were studied using immunohistochemistry and mutation analysis. Accumulation of p53 protein was detected in 10 out of 62 (16%) DCIS, whereas no cases of positive staining was observed in the atypical lesions. TP53 mutations were identified in four out of 30 (13%) DCIS by constant denaturant gel electrophoresis (CDGE). Two of these cases were positive and two negative for p53 protein. A total of 12 out of 62 DCIS (19%) carried TP53 mutation and/or p53 protein over-expression. The present results suggest that TP53 alterations may be important in the development of a subset of DCIS.