Differential distribution of ErbB-2 and pS2 proteins in ductal carcinoma in situ of the breast.

We examined the expression of ErbB-2 and pS2 proteins in 59 ductal carcinoma in situ (DCIS) of the breast, either pure DCIS or DCIS associated with invasive carcinoma, using immunohistochemical staining of paraffin-embedded sections. Positive staining for ErbB-2 and pS2 proteins was noted in 32% (19/59) and 46% (27/59) of DCIS, respectively. An inverse relationship between ErbB-2 and pS2 status in DCIS was observed (p < 0.01). From the viewpoint of histological subtype, the prevalence of ErbB-2 protein expression was significantly higher in the comedo subtype than the cribriform-micropapillary subtype. The prevalence of immunoreactivity for ErbB-2 in solid subtype was intermediate between those of the other two groups. In contrast, the prevalence of pS2 expression was significantly lower in the comedo subtype than in the cribriform-micropapillary subtype. Again, the prevalence of pS2 protein expression in the solid subtype was intermediate between those of the other two subtypes. Our results suggest that DCIS is biologically heterogeneous with regard to such marker substances. This has possible implications for management of these lesions.