Immunohistochemical visualisation of cathepsin-D expression in breast cancer.

Background: Cathepsin D (Cath-D), a lysosomal protease, is considered to be involved in the breakdown of the extracellular matrix during the process of tumour metastasis. Its expression in breast cancer in association with known factors of prognosis was investigated in this study.

Material And Methods: 120 breast cancer tumours were analysed immunohistochemically and evaluated with the immunoreactive score (IRS). Statistical evaluation was performed using the Mann-Whitney test (p < 0.05).

Results: For nodal-positive tumors we found a statistically significant increase of Cath-D immunohistochemical reaction. Ductal carcinomas showed a significantly higher immunohistochemical reaction compared to lobular carcinomas. We found a non-significant increase from G1 to G2 and G1 to G3, and a non-significant increase of Cath-D expression of all receptor-positive over all receptor-negative tumours.

Conclusion: Cath-D expression was found to be associated with known prognostic factors. The clinical relevance of the observed difference depending on the histological type needs further investigation. Cath-D might be a useful marker to discriminate between ductal and lobular subtypes of breast cancer.