IMMUNOHISTOCHEMICAL DETECTION OF GLUTATHIONE S-TRANSFERASE (GST) -π IN HEAD AND NECK CARCINOMA AND ITS CHANGE BY RADIOTHERAPY

Abstract

It is well known that the "placental form of glutathione S-transferase" (GST-pi) is present in high concentrations in most human carcinomas. However, its expression in head and neck carcinomas have not yet been reported. The author investigated the expression of GST-pi in the tissue of pharyngeal and laryngeal carcinomas by the immunohistochemical procedure, and the following results were obtained: 1) GST-pi was positive in 80% of laryngeal carcinomas (35 cases) and 52.8% of pharyngeal carcinomas (36 cases). As a rule, well differentiated squamous cell carcinomas showed stronger expression of GST-pi than poorly differentiated squamous cell carcinomas. 2) Although normal epithelia of the pharynx and larynx showed negative GST-pi, it should be noticed that 54.6% of precancerous epithelia (11 cases) showed positive GST-pi. 3) Most patients treated with radiotherapy showed the diminution of GST-pi expression after the irradiation. However, co-relation between the strength of initial GST-pi expression and the effectiveness of radiotherapy was not observed (p < 0.01).