Expression of HER-2/neu oncoprotein and epidermal growth factor receptor and prognosis in gastric carcinoma.

Fifty-six specimens of gastric carcinoma were examined for the localization of HER-2/neu oncoprotein (HER-2/neu) and epidermal growth factor receptor (EGFR) by immunohistochemistry using polyclonal antibodies on paraffin-embedded material. Strong membrane staining for HER-2/neu was noted in 14 cases (25%), all of which were of the intestinal type. Only cytoplasmic staining was found in an additional 21 cases (37.5%), including seven diffuse tumors. Twenty-four cases (nine diffuse and 15 intestinal) showed cytoplasmic staining with accentuation on the cell membrane for EGFR. Patchy staining was common for HER-2/neu, while EGFR immunoreactivity was always diffuse. Twenty cases (35.7%) showed positive staining for both, 15 cases (26.8%) for HER-2/neu only, four cases (7.1%) for EGFR only, and 17 cases (30.4%) for neither. Expression of HER-2/neu was more commonly associated with intermediate-grade and high-stage tumors. Cases with positive (either membrane or cytoplasmic) staining for HER-2/neu showed poorer overall mean survival (308 days) than cases that failed to stain (763 days). The EGFR-positive cases showed shorter mean survival (387 days) than the negative cases (547 days), but this difference did not reach statistical significance. The EGFR positivity did not further reduce survival in HER-2/neu-positive cases (362 days). The results of this study support the hypothesis that the expression of HER-2/neu may be a significant predictor of prognosis in patients with gastric carcinoma. Our findings also suggest that expression of these two closely related protooncogenes in malignant and benign gastric tissues is independent of each other and that EGFR does not potentiate the oncogenic effect of HER-2/neu.