Prognostic value of immunohistochemical expression of the c-erbB-2 oncoprotein in metastasic prostate cancer.

It is well established that the activation of proto-oncogenes could trigger uncontrolled cell growth and cancer development. Although this correlation has already been evidenced in several human tumors, no conclusive studies have related oncogene activation with the development of prostatic neoplasia. Nevertheless, some reports suggest that c-erbB-2, which is a prognostic marker in breast cancer, could be implicated in the development of prostatic adenocarcinoma. We have studied the expression of the c-erbB-2 oncoprotein in primary prostatic tissue in a series of 70 patients with metastasic disease, by means of immunohistochemistry. The NCL-B 11 anti-c-erbB-2 monoclonal antibody was used, and the immunoreactivity was quantified by image analysis. The overall rate of prostatic-tissue sections presenting positive c-erbB-2 immunostaining was 64.3%. No significant relation was observed between histological grade and c-erbB-2 over-expression or severity of the disease, based on the extent of metastases. The average specific survival in patients with c-erbB-2 over-expression was 33 months, while it was 54 in patients with c-erbB-2 negativity; p < 0. 034. These results, as well as the logistic-regression analysis, suggest that expression of c-erbB-2 oncoprotein would be considered as an independent prognostic factor of metastatic prostate cancer. Moreover, it could discriminate between the prognosis of patients with Gleason score 2 to 7 and those with score 8 to 10. Our results suggest that the expression of c-erbB-2 oncoprotein in primary prostatic tissue could have a prognostic value in patients with metastatic prostate cancer. Int. J. Cancer (Pred. Oncol.) 84:421-425, 1999.