c-erbB2 encodes 185 kDa oncoprotein with tyrosine kinase activity and has homology to the epidermal growth factor receptor. c-erbB2 proto-oncogene is found to be overexpressed in approximately 20 to 30% of primary breast cancer and has been associated with poor prognosis and lower response to conventional chemotherapy.

We performed a study on 40 infiltrating ductal breast cancers treated with primary surgery and adjuvant chemotherapy. We investigated c-erbB2 expression by immunohistochemistry in paraffin-embedded tissue using polyclonal antipeptide antibody (DAKO). We evaluated the relationships between its expression and the results after over 6 cycles of adjuvant chemotherapy including cyclophosphamide, methotrexate and 5-FU.

The median age at diagnosis was 43 years and the median follow-up time was 47.3 months. Thirteen (32.1 %) of 40 patients showed the c-erbB2 overexpression in the external domains of protein. There were no correlations among c-erbB2 amplification and other prognostic factors such as hormonal receptors, histologic grade and tumor size. Estrogen receptor and progesterone receptor showed tendency of inverse correlation with c-erbB2 overexpression but it was not statistically significant (p>0.05). c-erbB2 positive patients showed shorter disease free survival compared to c-erbB2 negative patients in univariate analysis (p<0.05)(Kaplan Meire analysis). The patients without c-erbB2 overexpression seemed to survive longer but had no significant survival benefit (p>0.05).

These findings suggest that overexpression of c-erbB2 may be a marker of poor response to adjuvant chemotherapy with CMF regimen and may be an indicator of more aggressive therapy.