Our study population comprised 10 normal breasts, 25 ductal carcinomas in situ (DCIS), and 51 invasive breast carcinomas. Immunohistochemical overexpressions of COX-2 and HER-2/neu were investigated in sections of formalin-fixed, paraffin-embedded blocks by 3 observers.
In normal breast, DCIS and IBC, the COX-2 overexpression rate was 0 % , 84 % , and 58.8 % , respectively. In IBC, COX-2 overexpression had a significant relationship with HER-2/neu overexpression (p = 0.026) and a high histological grade (p = 0.026). COX-2 expression in both DCIS (n = 25) and IBC (n = 51) was significantly higher than in normal breast tissue (p < 0.0001). In addition, the COX-2 expression rate was significantly higher in DCIS than in IBC (p = 0.042).
Our results indicated that COX-2 overexpression correlates with aggressive phenotypic features, such as HER-2/neu overexpression and high histological grade in IBC. Increased expression of COX-2 in both DCIS and IBC in comparison to normal breast could indicate a role in breast carcinogenesis. COX-2 overexpression may provide a clinically useful biomarker for estimating tumor aggressiveness.