P53 EXPRESSION IN MULTICENTRIC SQUAMOUS-CELL CARCINOMA AND SURROUNDING SQUAMOUS EPITHELIUM OF THE UPPER AERODIGESTIVE TRACT - IMMUNOHISTOCHEMICAL ANALYSIS OF 95 LESIONS

Background. It is now well documented that patients with squamous cell carcinoma of the upper aerodigestive tract frequently develop additio nal squamous cell carcinoma in the same field. Methods. p53 expression in 95 patients with multicentric squamous cell carcinoma and in squam ous epithelia surrounding multicentric squamous cell carcinomas of the upper aerodigestive tract in 20 patients was examined by immunohistoc hemistry. In addition, p53 expression in 129 patients with supposedly unicentric squamous cell carcinoma and in squamous epithelia surroundi ng unicentric squamous cell carcinoma in 22 patients was also examined by immunohistochemistry.Results. Among the 95 patients with multicent ric squamous cell carcinoma, 62 (65%) had a clearly positive reaction for p53 protein, whereas 56 (43%) of 129 patients with unicentric squa mous cell carcinoma had a positive reaction for p53 protein. The frequ ency of positive nuclear p53 staining in multicentric squamous cell ca rcinoma appeared higher than that in unicentric squamous cell carcinom a. However, there was no significant difference between the two groups . Among the nondysplastic squamous epithelia surrounding multicentric squamous cell carcinomas in 20 patients, 12 (60%) were p53 positive, w hereas only five (22%) of 22 patients with nondysplastic squamous epit helia surrounding unicentric squamous cell carcinomas were positive. T he difference between the two groups was significant (P < 0.05). Concl usions. The present results suggest that nuclear accumulation of p53 i n the squamous epithelium surrounding multicentric squamous cell carci noma is probably due to heavier exposure and increased susceptibility to mutagens of the affected individuals, although this remains to be v erified.