Clinical significance of carcinoembryonic antigen expression of acellular mucin pools after preoperative chemoradiotherapy of rectal carcinoma

摘要

Introduction: Although several studies have shown that the presence of acellular mucin pools in surgical specimens with rectal carcinomas examined after preoperative chemoradiotherapy indicated complete response to therapy, the proper meaning of these pools has yet to be elucidated. The aims of this study were to analyze the immunoprofile of acellular mucin pools and to review the relevant literature. Methods: In 30 consecutive rectal cancers that were preoperatively treated with chemoradiotherapy, the clinicopathologic features were correlated with the immunoexpression of AE1/AE3 keratin and carcinoembryonic antigen (CEA). Results: Acellular mucin pools were present in all the cases, independently by their preoperative histological aspect. In remnant tumors (n=20), they were present at the invasion front and were marked by CEA. In cases without remnant tumor cells (n=10), they also displayed CEA positivity. In 2 of the 10 cases, isolated tumor cells were identified after multilevel sectioning of paraffin-embedded blocks. Conclusions: The presence of acellular mucin pools in surgical specimens of rectal cancers cannot be interpreted as an indicator of complete response to radiotherapy if at least 10 multilevel sections are performed in at least three tumor blocks per case, and CEA negativity is not proved.