Epidermal growth factor receptor expression in pre-invasive and early invasive bronchial lesions.

The 1999 World Health Organization/International Association for the Study of Lung Cancer histological classification of preneoplastic bronchial lesions has been shown to be reproducible but little is known about its biological significance. The current study evaluated the correspondence between the morphological changes of the bronchial epithelium and epidermal growth factor receptor (EGF-R) expression. Thirteen normal bronchial epithelia, 19 hyperplasia, 16 metaplasia, 10 mild dysplasia, one moderate dysplasia, 10 severe dysplasia (SD), 14 carcinoma in situ (CIS) and 11 microinvasive tumours were assessed. A global EGF-R score obtained by the sum of the positivity score plus the EGF-R staining intensity score was calculated for each lesion. A global EGF-R score of >5 was reached only in one metaplasia, in six SD, in six CIS and in six microinvasive tumours. There was no difference in EGF-R expression between normal, hyperplastic and metaplastic epithelia versus mild dysplasia or between severe dysplasia versus CIS and microinvasive tumours but there was a statistically significant difference between mild versus severe dysplasia. This study demonstrates that epidermal growth factor receptor expression rate changes with the stage of the bronchial lesion, increasing from normal epithelium to carcinoma in situ and microinvasive tumours with a statistically significant difference between mild versus severe dysplasia.