Background: Cathepsin D (CatD) can facilitate the invasive behaviour of breast cancer cells and thus plays a key role in the mechanism of invasion and metastasis.
Materials and method: The expression of the protease CatD was evaluated using an immunohistochemical technique with a polyclonal antibody on paraffin-embedded tissue from 80 women treated for invasive ductal mammary carcinoma not otherwise specified (NOS).
Results: Thirty seven tumours (46%) showed prominent staining of cells in the tumour. Neoplastic cell staining for CatD correlated with axillary nodal involvement (p < 0.05), high oestrogen receptor positivity status (p < 0.01) and low or moderate tumour grade (p < 0.05). Stromal cell (primarily histiocyte) CatD immunostaining was frequently noticed and was proportional to the degree of the intratumoural inflammatory infiltrate.
Conclusions: Cat D detection in neoplastic cells is likely to be involved in the invasive capability of well differentiated breast cancer cells, but it may simultaneously reflect the functional integrity of the oestrogen response pathway, commonly observed in well-differentiated tumours.