Immunohistochemical study of c-erbB-2 protein in colorectal cancer and the correlation with patient survival.

We related events in immunohistochemical studies on formalin-fixed, paraffin-embedded preparations of 146 colorectal cancer patients. One hundred (68.5%) revealed cytoplasmic staining and only 3 of the 100 showed membranous staining. Western blot analysis revealed proteins with molecular masses of 185 and 155 kD following immunohistochemical membranous and cytoplasmic staining, but only a 155-kD protein following cytoplasmic staining. Amplification of the c-erbB-2 gene was detected in 2 of 44 cases (4.5%). Cytoplasmic c-erbB-2 overexpression correlated with tumor size (p < 0.01), subserosal invasion (p < 0.05), liver metastasis (p < 0.01) and Dukes' classification. Overall survival rates and survival rates for Dukes'B patients were significantly lower in the group with cytoplasmic c-erbB-2 overexpression than in the group without cytoplasmic c-erbB-2 overexpression. Multivariate regression analysis showed cytoplasmic c-erbB-2 overexpression to be an independent prognostic factor for colorectal cancer. These results suggest that overexpression of cytoplasmic c-erbB-2 protein plays an important role in the progression of colorectal cancer and is considered to be an independent prognostic indicator of this lesion.