Mucins in neoplastic spectrum of colorectal polyps: can they provide predictions?

Background: The significance of expression of different mucins in succession of malignant transformation of colorectal polyps is not determined yet. The aim of the present study was to determine the pattern of expression of MUC1, MUC2, MUC5AC and MUC6 in colorectal polyps and to evaluate the applicability of using mucin expression in predicting the extent of malignant transformation in colorectal polyps.

Methods: A total of 454 polyp specimens comprising 36 hyperplastic polyps, 15 serrated adenomas, 258 tubular adenomas, 114 tubulovillous adenomas, and 31 villous adenomas were included in this study, and were immunostained for MUC1, MUC2, MUC5AC and MUC6 by using mucin specific antibodies.

Results: MUC1 and MUC6 were absent in all hyperplastic polyps and their expression was higher in serrated and traditional adenomas. Only 5 cases including 2 serrated adenomas, 1 tubulovillous adenoma, and 2 villous adenomas stained negative for MUC2. The highest expression of MUC5AC was observed in serrated adenomas followed by tubular adenomas. Binary logistic regression analysis indicated that positive staining for MUC1, and MUC6, and negative staining for MUC2 would increase the risk of invasion to mucosa or the muscularis mucosae in colorectal polyps. Ordinal regression analysis demonstrated a positive association between the level of staining for MUC1 and risk of being of high configuration/grade in colorectal polyps.

Conclusions: MUC1, MUC2, MUC5AC, and MUC6 have the potential to be used as predictors of malignant transformation and invasion to mucosa or the muscularis mucosae in colorectal polyps. The most reliable predictions can be achieved by determining the level of expression of MUC1.