Cathepsin D levels in primary breast cancers: relationship with epidermal growth factor receptor, oestrogen receptor and axillary nodal status.

Cathepsin D and the epidermal growth factor receptor (EGFr) have both been proposed as poor prognostic markers in breast cancer. We have compared the tumour cytosolic cathepsin D level with EGFr and oestrogen receptor (ER) levels and the axillary node status of 131 patients with operable breast cancer, to see if EGFr and cathepsin D are co-regulated. Cathepsin D level was measured using a two-site immunoradiometric assay kit. No correlation was found between the level of cathepsin D and EGFr, ER or nodal status. Since the raised level of cytosolic cathepsin D was not related to EGFr, it may be that measuring the level of both of these markers in the same sample will give additional prognostic information.