Relationship of a new histological categorization of ductal carcinoma in situ of the breast with size and the immunohistochemical expression of p53, c-erb B2, bcl-2, and ki-67

Ductal carcinoma in situ (DCIS) represents a heterogeneous group of diseases. There is no generally accepted classification for the different cytological and architectural types of DCIS. A recent study (Scott et al, 1995) indicates that over 90% of DCIS can be easily classified into the following five categories: high grade (HG), intermediate grade (IG), low grade (LG), pure micropapillary (M), and pure apocrine (A). The aim of this study was to determine if there is a relationship between lesion size and the immunohistochemical expression of p53, c-erb B2, bcl-2, and ki67 with this reproducible categorization of DCIS. Seventy cases of DCIS diagnosed between 1984 and 1995 were obtained from the Departments of Pathology at two teaching hospitals in London, Ontario. The original sections were reviewed, classified according to Scott et al (1995), and representative sections were cut for immunohistochemical (IHC) studies. IHC stains were scored using a previously described semiquantitative scoring system (Allred et al, 1993). Size was taken from the gross measurement if the lesion was palpable or recorded as the largest dimension, as measured on the histological slide, for nonpalpable cases. Of the 70 DCIS cases, 17 (24.3%) were HG, 23 (32.9%) were IG, 21 (30%) were LG, seven (10%) were pure micropapillary cases, and two (2.9%) were pure apocrine DCIS. The mean size of the DCIS for each subcategory was statistically significantly different ( P = .008). In particular, the micropapillary DCIS cases were largest (mean size, 17 mm). The mean immunohistochemical scores for c-erb B2 for each category were also statistically different ( P = .007), whereas the mean scores for p53 and ki67 for each category trended toward significance ( P = .073, P = .062, respectively). There were no significant differences between bcl-2 mean scores and each subcategory. Size of DCIS and c-erb B2 positivity are known to be associated with more aggressive clinical behavior and more advanced histologic features, respectively. Because this combined histological cytological classification system is predictive of size and c-erb B2 positivity, our results support the clinical relevance of this classification system.