C-ERBB-2 ONCOPROTEIN IN RELATION TO DNA-PLOIDY AND PROGNOSIS IN COLORECTAL ADENOCARCINOMA

Overexpression of the c-erbB-2 onocogene has been demonstrated in a va riety of tumours, including colorectal tumours. In breast carcinoma, c -erbB-2 overexpression is associated with DNA ploidy, some other progn ostic indicators, and unfavourable survival prospects. However, there is little such information available regarding colorectal tumours. In this study, c-erbB-2 was analysed retrospectively by immunohistochemis try in 293 primary colorectal adenocarcinomas to assess its relation t o DNA ploidy, S-phase fraction, other prognostic factors, and patient survival. Using the monoclonal antibody NCL-CB11, we found that 23% of the tumours were strongly c-erbB-2 positive, while 36% showed weak ex pression. The highest frequency of c-erbB-2 expression was 81% in DNA tetraploid tumours, compared to 63% in aneuploid and, 53% in diploid t umours (test for heterogeneity, p=0.031). Overexpression of c-erbB-2 i ndicated a favourable prognosis in patients with DNA aneuploid tumours (p=0.0088), but not in those with diploid or tetraploid tumours. The prognostic value of c-erbB-2 in DNA aneuploid tumours remained even af ter adjustment for Dukes' stage (p=0.027). The results suggest that a combination of c-erbB-2 expression and DNA ploidy may improve the iden tification of patients' risk of cancer death.