Expression of amphiregulin and epidermal growth factor receptor in human breast cancer: analysis of autocriny and stromal-epithelial interactions.

Amphiregulin (AR) and its receptor, epidermal growth factor receptor (EGFR), were evaluated by dual immunostaining in a series of 84 invasive ductal breast carcinoma specimens, 33 of which were from locally advanced inflammatory (T4d) cancer. Co-expression of AR and EGFR was always found in non-malignant breast tissues adjacent to tumours (24/24). Alternatively, expression of AR and EGFR was found in invasive epithelial tumour cells in 50% and 17.8% of specimens, respectively. In tumour stroma, 59.5% and 30.9% of specimens, respectively, were positively stained. By univariate analysis, AR and EGFR expression in invasive carcinomas was correlated with large tumour size, inflammatory carcinoma, node involvement, Bloom-Richardson (SBR) grade III, and absence of oestrogen receptor. EGFR expression in stromal cells was correlated with non-inflammatory carcinoma. A putative autocrine loop with AR and EGFR expression in invasive carcinoma was detected in 14.3% of cases. Stromal expression of AR and EGFR expression in invasive tumour cells was detected in 11.9% of cases and related to poor prognostic parameters. By multivariate analysis, AR expression in invasive tumour was strongly related to inflammatory carcinoma (p=0.005) and marginally related to SBR grade III (p=0.07). EGFR expression in invasive tumour and stromal cells was correlated with absence of oestrogen receptor and non-inflammatory carcinoma (p=0.002 and p=0.015, respectively). Copyright 2001 John Wiley & Sons, Ltd.