In situ evaluation of the relationship between epidermal-growth-factor-receptor status and tumor-cell proliferation in colon carcinomas.

The association between the expression of the epidermal-growth-factor receptor (EGFR) and tumor proliferation was studied in 69 resected human adenocarcinomas of the colon. EGFR was detected immunohistochemically using the monoclonal antibody (MAb) EGFRI. Tumor-cell proliferation was assessed with the MAb Ki-67 directed against a proliferation-associated nuclear antigen expressed only in proliferating cells. The percentage of Ki-67-positive tumor cells (Ki-67 index) was evaluated by the point-counting method. Forty-seven carcinomas contained detectable EGFR immunoreactivity. Statistical analysis failed to reveal correlations between the EGFR status and T, N and M stages or tumor differentiation. The mean Ki-67 index did not differ between EGFR-positive and -negative carcinomas. Seven tumors contained clearly distinguishable areas with different EGFR staining intensity. In these tumors with a locally heterogeneous EGFR expression, tumor proliferation also did not correlate with EGFR immunoreactivity. These in situ observations suggest that EGFR expression may not play an important role in the growth regulation of human colonic carcinomas.