Prognostic value of cathepsin D expression and association with histomorphological subtypes in breast cancer

This study investigated the prognostic value of immunohistochemically detected cathepsin D expression in 103 invasive ductal carcinomas of the breast at stages pT1 and 2. We also assessed the association between cathepsin D expression and histomorphological tumour subtypes (invasive ductal carcinoma with extensive intraductal component, multifocal tumour). Cathepsin D expression was examined at two cut-off levels (positive and highly positive) and separately identified within the epithelial and stromal component of all tumours. Positive and highly positive epithelial expression was detected in 32 (31.1%) and 20 (19.4%) patients respectively. Stromal expression was found in 35 (34%) and 19 (18.4%) cases respectively. Epithelial cathepsin D expression was associated with stage and nuclear grade, but not with lymph node or oestrogen receptor status. Positive and highly positive epithelial cathepsin D expression showed significant prognostic value for overall survival (P = 0.003 and 0.01) and recurrence-free interval (P = 0.04 and 0.02). Cathepsin D expression in stromal cells was not associated with either several established prognostic factors or survival. Multivariate analysis revealed that cathepsin D expression failed to be an independent predictor of patients' outcome. Cathepsin D expression shows no significant association with histomorphological subtypes of breast cancer. Our study supports the prognostic impact of immunohistochemically detected cathepsin D expression in the epithelial component of breast cancer.