Cathepsin D, a lysosomal protease has been proposed to playa role in the local invasion and metastatic dissemination in primary breast cancer. Although there are many conflicting results, the overexpression of cathepsin D has been considered to be related with a poorer prognosis of breast cancer. This study was designed to verify whether cathepsin D expression is related to other prognostic factors in breast cancer.

Cathepsin D was assessed by immunohistochemistry using murine monoclonal anti-cathepsin D antibody (ZyMED) in 79 paraffin-embedded primary breast cancer specimens. Cathepsin D expression was compared to other prognostic parameters such as tumor size, axillary lymph node metastasis, tumor histologic grades, hormone receptors (ER & PRJ, p53, c-erb 82, Ki-67, MVD (microvessel density), and Pgp (P-glycoprotein).

A high-expression of cathepsin D was found in 35 of 79 patients (44.3%) with primary breast cancer. Cathepsin D expression was not related to tumor size, axillary lymph node metastasis, tumor histologic grades, hormone receptors, p53, Ki-67, or CD31. However, a significant relationship was found between cathepsin D expression and c-erb 82 (p=0.007), and between cathepsin D expression and Pgp (p=0.003).

These results suggest that cathepsin D expression may be an indicator of a poor prognosis in breast cancer. However, further studies are required to verify the exact role of cathepsin D in the prognosis of breast cancer.