Prognostic significance of immunohistochemical c-erbB-2 proto-oncogene expression and nuclear DNA content in human breast cancer.

Immunoreactivity of the c-erbB-2 proto-oncogene product and nuclear DNA content were assessed in specimens from 211 breast cancer patients with a mean follow-up of 16 years (range 13-19 years). A routine immunoperoxidase technique was used and cytometrical DNA assessments were performed on cytodiagnostically identified tumour nuclei, using image analysis. C-erbB-2 cell membrane staining was observed in 29% of the cases and was found to be related to tumour size (P = 0.02), histopathological grade (P = 0.02) and nuclear DNA content (P < 0.01). In univariate analysis immunohistochemical c-erbB-2 expression was of prognostic significance among node-positive patients (P = 0.02), but not among women with node-negative disease. This prognostic ability was reduced by multivariate analysis and was no longer significant. In contrast, nuclear DNA content was significantly related to distant recurrence-free survival even in multivariate analysis after adjustment for nodal status and tumour size (P < 0.01). In conclusion, the findings of the present study indicate that c-erbB-2 expression is of limited prognostic value in a subgroup of patients, whereas nuclear DNA content seems to provide significant prognostic information even in node-negative patients.