A FOLLOW-UP-STUDY OF PROGRESSION FROM DYSPLASIA TO SQUAMOUS-CELL CARCINOMA WITH IMMUNOHISTOCHEMICAL EXAMINATION OF P53 PROTEIN OVEREXPRESSION IN THE BRONCHI OF EX-CHROMATE WORKERS

Squamous cell carcinoma (SCC) of the bronchus is considered to develop from preneoplastic 'dysplasia', but reports of sequential observation of this dysplasia-carcinoma sequence in humans are very few. We follo wed four dysplastic lesions found in the bronchi of three ex-chromate workers by bronchoscopy and biopsy and found that all of them progress ed to SCC. Of the four lesions, three were severe dysplasias at the fi rst biopsy which progressed to SCCs in 7-13 months, The last one was a slight dysplasia at the first biopsy and showed progression of the at ypia to carcinoma in 6 years and 10 months. An immunohistochemical ana lysis of the chronological change in p53 protein expression in these l esions and in normal ciliated epithelium taken from the surroundings w as conducted in each case. Overexpression of p53 protein was observed in two of the severe dysplasias and the one slight dysplasia, as well as their eventual SCCs. However, no such change was apparent in one ca se of severe dysplasia or its eventual SCC. Normal epithelium was cons istently negative. Our results provide direct proof of the dysplasia-c arcinoma sequence and suggest that alteration in the expression of p53 protein might be an important early event which persists. Therefore, the immunohistochemical detection of p53 overexpression in biopsy spec imens of bronchial epithelium might be useful for evaluation of preneo plastic lesions in high-risk group individuals and for early diagnosis of bronchial cancer.