Cell proliferation in breast carcinoma assessed by a PCNA grading system and its relation to other prognostic variables.

This study was undertaken to relate the expression of the proliferating cell nuclear antigen (PCNA), a proliferation marker of putative prognostic significance, to some more established prognostic factors in a series of 60 consecutive breast cancer surgical specimens. PCNA was detected by the PC10 monoclonal antibody (MAb) using an immunohistochemical method and PCNA immunostaining was estimated on a semiquantitative basis, a cut-off value of 50% of positively stained tumour cells discriminating between the high (> 50%) and low (< 50%) PCNA grade. The PCNA grade did not correlate with tumour size and axillary node status. However, a high PCNA grade tended to be associated with a poor histological grade and there was an inverse relationship with oestrogen-receptor status, as determined by means of the immuno-histochemical staining for the oestrogen-induced pS2 protein. These conflicting results suggest that the possible prognostic usefulness of PCNA immunostaining, as a measure of cell proliferation rate, in breast cancer is yet to be demonstrated and can be validated only by direct relation to survival data.