[Immunohistochemical studies on expression of epidermal growth factor receptor (EGFR) and proliferative activity in...

Expressions of epidermal growth factor receptor (EGFR) were studied immunohistochemically in a total of 101 human colorectal cancers, and compared with clinicopathological findings. DNA polymerase alpha, a marker of the proliferating cells, was stained immunohistochemically in 26 cases in which fresh and frozen sections were obtained, and growth fraction was calculated as labeling index. EGFR positive tumor cells were detected in 17 cases (16.8%) of the 101 colorectal cancers. Significantly high incidence of EGFR expression was observed in more deeply invasive tumors, larger tumor sizes and more infiltrating macroscopic types. No significant differences, however, were observed between EGFR-positive and EFGR-negative cases regarding lymphnode metastasis, histopathological classification and pathological staging. DNA polymerase alpha laveling index was 597.9 +/- 76.6, and 428.4 +/- 140.2 in EGFR-positive cases, and EGFR-negative cases, respectively. There was a significant (p < 0.01) correlation between DNA polymerase alpha labeling index and EGFR status. These results indicate that EGFR positive cases in colorectal cancers have higher proliferative activity and more invasive stage, compared with EGFR negative cases, and suggest that EGFR produced by tumor cells play an important role in the progression and proliferation of colorectal cancers.