IMMUNOHISTOCHEMICAL DETECTION OF BCL-2 PROTEIN IN SMALL-CELL CARCINOMAS

The expression of Bcl-2 protein in 29 small cell carcinomas (SCCs; 6 s urgical and 15 biopsy specimens obtained from various organs, 7 metast atic lymph nodes, and 1 metastatic liver tissue) was investigated by i mmunohistochemical technique. Negative staining was observed in only t wo cases (7%). The majority of Bcl-2-positive tumors had >95% positive cells, with a moderate staining intensity. A combined small-cell lung cancer showed discordant staining results between two different histo logy types. No correlations of Bcl-2 immunoreactivity with p53 express ion and clinical staging were found. Our findings suggest that Bcl-2 e xpression may play a certain role in the early phases of SCC tumorigen esis, or that it may solely be a succeeding property directly derived from the tumor progenitor cells. As the Bcl-2 protein was present in m ost cases, it is not a useful prognostic or treatment marker for the c ancer.