FasL expression during progression of colorectal carcinogenesis and its potential prognostic implication

Background: Fast expressing tumor cells maybe able to eliminate activated T -cells via Fas/FasL induced apoptosis. Methods: We analysed by means of immunhistchemistry the Fast protein expres sion in colorectal normal mucosa, transitional mucosa, adenomas, carcinomas and their liver metastases on paraffin tissue sections of 171 patients wit h known follow-up Results: Adenomas expressed Fast more strongly than the transitional mucosa . This expression was further increased in carcinomas, with no differences during the progression of the tumor stage. However, Fast expression in the transitional mucosa showed a significant increase during the progression of the primary carcinoma and was of prognostic relevance in univariate analys is. Conclusion: This finding suggests a paracrine regulation of the Fast-expres sion in the transitional mucosa through the carcinoma cells.