Encapsulated papillary carcinoma of the breast: a study of invasion associated markers

Encapsulated papillary carcinoma (EPC) of the breast is a distinct histological subtype characterised by malignant epithelial proliferation supported by fibrovascular stalks. Although EPC typically lacks myoepithelial cells, it shows indolent clinical course. The classification of EPC as an in situ, or invasive disease, remains a matter of debate. Methods In this study, the authors investigated a panel of invasion-associated markers in a series of EPC and compared their expression with control groups of non-papillary ductal carcinoma in situ (DCIS) and conventional invasive carcinomas. The expression pattern of four matrix metalloproteinases (MMP-1, MMP-2, MMP-7 and MMP-9), transforming growth factor receptor beta, vascular endothelial growth factor (VEGF) and E-cadherin were assessed in the tumour cell and/or stromal tissue, and the results were analysed. Results EPC showed higher expression levels of both MMP-1 and MMP-9 compared with DCIS, and no significant differences were observed between EPC and invasive carcinoma. Expression of MMP-2 and MMP-7 levels were similar in EPC and DCIS, but both showed lower levels compared with invasive tumours. EPC showed higher expression of E-cadherin and transforming growth factor receptor beta 1 compared with both DCIS and invasive cancer. No difference in the stromal expression of MMPs or tumour expression of VEGF was detected. Conclusion EPC exhibits an expression pattern of invasion-associated markers, which is intermediate in nature between DCIS and invasive cancer, providing further support of the unique biological features of EPC, and which may explain its clinically indolent behaviour.