C-ERBB-2 ONCOGENE PRODUCT EXPRESSION DEPENDS ON TUMOR TYPE AND IS RELATED TO ESTROGEN-RECEPTOR AND LYMPH-NODE STATUS IN HUMAN BREAST-CARCINOMA

Although over-expression of the C-erbB-2 oncogene product can be detec ted on formalin-fixed, paraffin-embedded sections from tumours of the human breast, fixation results in a considerable loss of immunostainin g for this protein. In this study, C-erbB-2 expression was studied imm unohistochemically on frozen sections in 63 infiltrating carcinomas, 3 phyllodes tumours, 15 fibroadenomas and 1 6 cases of fibrocystic dise ase. The value of C-erbB-2 expression as a prognostic indicator in duc tal carcinomas was examined by seeking an association with known progn ostic indicators. C-erbB-2 over-expression was confined to ductal carc inomas of the breast and was positively correlated with tumour size, g rade, oestrogen receptor status and the presence of metastatic deposit s in axillary lymph nodes. Only the association with lymph node and oe strogen receptor status were statistically significant. No evidence of a correlation between C-erbB-2 expression and growth fraction (as ass essed with. the Ki-67 antibody) was demonstrated in the cases studied. Formalin fixation was associated with the loss of immunoreactivity in all cases studied. 75% of cases which were positive on frozen section s were negative in paraffin sections. These results highlight the sign ificance of the method of fixation used in studying C-erbB-2 expressio n. They confirm the association between C-erbB-2 expression and known prognostic indicators.